O

O — observable (adj.)

O

fifteenth letter of the alphabet, from a character that in Phoenician was called 'ain (literally "eye") and represented "a very peculiar and to us unpronounceable guttural" [Century Dictionary]. The Greeks also lacked the sound, so when they adopted the Phoenician letters they arbitrarily changed O's value to a vowel. (Thus there is no grounds for the belief that the form of the letter represents the shape of the mouth in pronouncing it.) The Greeks later added a special character for "long" O (omega), and the original became "little o" (omicron).ETD O.2

In Middle English and later colloquial use, o or o' can be an abbreviation of on or of, and is still literary in some words (o'clock, Jack-o'-lantern, tam-o'-shanter, cat-o'-nine-tails, will-o'-the-wisp, etc.).ETD O.3

O' the common prefix in Irish surnames is from Irish ó, ua (Old Irish au, ui) "descendant."ETD O.4

The "connective" -o- is the usual connecting vowel in compounds taken or formed from Greek, where it often is the vowel in the stem. "[I]t is affixed, not only to terms of Greek origin, but also to those derived from Latin (Latin compounds of which would have been formed with the L. connecting or reduced thematic vowel, -i), especially when compounds are wanted with a sense that Latin composition, even if possible, would not warrant, but which would be authorized by the principles of Greek composition." [OED]ETD O.5

As "zero" in Arabic numerals it is attested from c. 1600, from the similarity of shape. Similarly the O blood type (1926) was originally "zero," denoting the absence of A and B agglutinogens.ETD O.6

As a gauge of track in model railroads, by 1905. For o as an interjection of fear, surprise, joy, etc., see oh.ETD O.7

The use of the colloquial or slang -o suffix in wino, ammo, combo, kiddo, the names of the Marx Brothers, etc., "is widespread in English-speaking countries but nowhere more so than in Australia" [OED 2nd. ed. print, 1989].ETD O.8

OED

initialism (acronym) of Oxford English Dictionary, attested from 1898, according to the "Oxford English Dictionary."ETD OED.2

oaf (n.)

1620s, auf, oph (modern form from 1630s; oafish is from 1610s), "a changeling; a foolish or otherwise defective child left by the fairies in place of another carried off," from a Scandinavian source such as Norwegian alfr "silly person," in Old Norse "elf" (see elf). Hence, "a misbegotten, deformed idiot, a simpleton" (17c.). Until recently, some dictionaries still gave the plural as oaves.ETD oaf (n.).2

oafish (adj.)

"like an oaf, stupid, dull," 1610s, from oaf + -ish. Related: Oafishly; oafishness.ETD oafish (adj.).2

oak (n.)

"tree or shrub of the genus Quercus," Middle English oke, from Old English ac "oak tree" and in part from cognate Old Norse eik, both from Proto-Germanic *aiks (source also of Old Saxon and Old Frisian ek, Middle Dutch eike, Dutch eik, Old High German eih, German Eiche, Swedish ek, Danish eg), a word of uncertain origin with no certain cognates outside Germanic.ETD oak (n.).2

The usual Indo-European base for "oak" (*deru-) has become Modern English tree (n.). In Greek and Celtic, meanwhile, words for "oak" are from the Indo-European root for "tree." All this probably reflects the importance of the oak, the monarch of the forest, to ancient Indo-Europeans. Likewise, as there were no oaks in Iceland, the Old Norse word eik came to be used by the viking settlers there for "tree" in general.ETD oak (n.).3

In English the word is used in Biblical translations to render Hebrew elah (probably usually "terebinth tree") and four other words. The form in Middle English was very uncertain (oc, oek, hokke, ake, eoke, aike, hock, etc.). Oak-gall "excrescence produced by an oak tree in reaction to insects," used in making ink, is by 1712.ETD oak (n.).4

oaken (adj.)

"made of, or consisting of, the wood of the oak," late 14c. (12c. in surnames and place-names), oken, from oak + -en (2). Similar formation in Old Frisian eken, Dutch eiken, Old High German eichen, German eichen, Old Norse eikinn.ETD oaken (adj.).2

oakum (n.)

"coarse, loose fiber obtained from taking apart old hemp ropes," used for caulking the seams of wooden ships, etc., early 15c., okam, okum, from Old English acumba "tow, oakum, flax fibers separated by combing," literally "what is combed out," from Proto-Germanic *us-kambon (source of Old High German achambi). The first element is cognate with Old English a- "away, out, off;" the second element is from stem of cemban "to comb," from camb "a comb;" from PIE root *gembh- "tooth, nail."ETD oakum (n.).2

oar (n.)

"long wooden lever for propelling a boat," Middle English or, from Old English ar, from Proto-Germanic *airo (source also of Old Norse ar, Danish aare, Swedish åra), a word of unknown origin. Apparently unrelated to the IE root that is the source of Latin remus "oar," Greek eretēs "rower," eretmos "oar," English row (v.) and rudder. As "oar-like appendage of an animal," 1580s.ETD oar (n.).2

oarlock (n.)

"hole or indentation in the gunwale of a boat where an oar rests," mid-14c., or-lok, from oar + lock (n.1).ETD oarlock (n.).2

oarsman (n.)

"one who rows with an oar," mid-15c., from genitive of oar (n.) + man (n.).ETD oarsman (n.).2

oasis (n.)

"fertile spot in a desert, where there is a spring or well and more or less vegetation," originally in reference to the Libyan desert, 1610s, from French oasis (18c.) and directly from Late Latin oasis, from Greek oasis, probably from Hamitic (compare Coptic wahe, ouahe "oasis," properly "dwelling place," from ouih "dwell"). The same Egyptian source produced Arabic wahah. Figurative sense of "any fertile place in the midst of a waste" is by 1800.ETD oasis (n.).2

oat (n.)

type of cereal plant, Middle English ote, from Old English ate (plural atan) "grain of the oat plant, wild oats," a word of uncertain origin, possibly from Old Norse eitill "nodule," denoting a single grain, itself of unknown origin. The English word has cognates in Frisian and some Dutch dialects. Famously defined by Johnson as, "A grain, which in England is generally given to horses, but in Scotland supports the people." Related: Oats.ETD oat (n.).2

The usual Germanic name is derived from Proto-Germanic *khabran (source also of Old Norse hafri, Dutch haver, source of haversack).ETD oat (n.).3

The figurative wild oats "youthful excesses" (the notion is "crop that one will regret sowing") is attested by 1560s, in reference to the folly of sowing these instead of good grain. (In Middle English to sow in the flesh was "be sinful, live carnally.") Hence also feel (one's) oats "be lively," 1831, originally American English.ETD oat (n.).4

oaten (adj.)

"consisting of oats or oatmeal," late 14c., oten, from oat + -en (2). Also "made of stem of the straw of oats," as shepherd's pipes were in poetry.ETD oaten (adj.).2

oater (n.)

"Western film" (featuring horse-riding cowboys and Indians), 1946, American English, from oat, as the typical food of horses. Oats opera (on the model of soap opera) is by 1937 in U.S. slang.ETD oater (n.).2

oath (n.)

Middle English oth, from Old English að "judicial swearing, solemn appeal (to deity, sacred relics, etc.), in witness of truth or a promise," from Proto-Germanic *aithaz (source also of Old Norse eiðr, Swedish ed, Old Saxon, Old Frisian eth, Middle Dutch eet, Dutch eed, German eid, Gothic aiþs "oath"), from PIE *oi-to- "an oath" (source also of Old Irish oeth "oath"). Common to Celtic and Germanic, possibly a loan-word from one to the other, but the history is obscure and it may ultimately be non-Indo-European. In reference to careless invocations of divinity, from late Old English.ETD oath (n.).2

oatmeal (n.)

"the coarsely ground meal of oats," late 14c., ote-mele, from oat + Middle English mele (see meal (n.2)).ETD oatmeal (n.).2

ob-

word-forming element meaning "toward; against; before; near; across; down," also used as an intensive, from Latin ob (prep.) "in the direction of, in front of, before; toward, to, at, upon, about; in the way of; with regard to, because of," from PIE root *epi, also *opi "near, against" (see epi-).ETD ob-.2

Obadiah

masc. proper name, fourth of the Twelve Prophets of the Old Testament, from Hebrew Obhadyah, literally "servant of the Lord," from abhadh "he served, worshipped," related to Arabic 'abada "he served," 'abd "slave, worshipper."ETD Obadiah.2

obambulation (n.)

"a walking about," c. 1600, from Latin obambulationem (nominative obambulatio) "a going or walking about," noun of action from past-participle stem of obambulare "to go or walk about, walk past, walk near," from ob "about" (see ob-) + ambulare "to walk, go about" (see amble (v.)).ETD obambulation (n.).2

obbligato (adj.)

musical instruction, used of accompaniments (especially by a single instrument, to a vocal piece), "so important that it cannot be omitted," 1724, from Italian obbligato, literally "obligated," from Latin obligatus, past participle of obligare "to bind" (see oblige). As a noun, "an accompaniment of independent importance," by 1817.ETD obbligato (adj.).2

obdurate (adj.)

mid-15c., "stubborn, inexorable, unyielding; hardened," especially against moral influences; "stubbornly wicked," from Latin obduratus "hardened," past participle of obdurare "harden, render hard; be hard or hardened; hold out, persist, endure," in Church Latin "to harden the heart against God," from ob "against" (see ob-) + durare "harden, render hard," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." Variant opturate is from early 15c. in medicine in a literal sense of "stopped, obstructed." Related: Obdurately; obdurateness.ETD obdurate (adj.).2

obduration (n.)

c. 1400, obduracioun, "hard-heartedness; defiant impenitence," from Late Latin obdurationem (nominative obduratio) "a hardening," noun of state from past-participle stem of Latin obdurare "harden, render hard; be hard or hardened" (see obdurate).ETD obduration (n.).2

obduracy (n.)

"stubbornness," especially "state of being hardened against moral influences, rebellious persistence in wickedness," 1590s, from obdurate + abstract noun suffix -cy.ETD obduracy (n.).2

obeah (n.)

"sorcery, witchcraft" among Africans in Africa and the West Indies, 1760, from a West African word, such as Efik (southern Nigeria) ubio "a thing or mixture left as a charm to cause sickness or death," Twi ebayifo "witch, wizard, sorcerer."ETD obeah (n.).2

obediently (adv.)

"in a compliant manner, dutifully," late 14c., from obedient + -ly (2).ETD obediently (adv.).2

obedient (adj.)

c. 1200, "willing to serve (someone); willing to fulfill an obligation," from Old French obedient "obedient" (11c.), from Latin oboedientem (nominative oboediens) "obedient, compliant," present participle of oboedire "to obey" (see obey).ETD obedient (adj.).2

obedience (n.)

c. 1200, "the practice or virtue of submission to a higher power or authority;" late 14c., "dutiful compliance with a command or law," from Old French obedience "obedience, submission" (12c.), from Latin oboedientia "obedience," abstract noun from oboedientem (nominative oboediens) "obedient, compliant," present participle of oboedire "to obey" (see obey). In reference to dog training from 1930.ETD obedience (n.).2

obey (v.)

c. 1300, obeien, "carry out the commands of (someone); submit to (a command, rule, etc.); be ruled by," from Old French obeir "obey, be obedient, do one's duty" (12c.), from Latin obedire, oboedire "obey, be subject, serve; pay attention to, give ear," literally "listen to," from ob "to" (see ob-) + audire "listen, hear" (from PIE root *au- "to perceive"). Same sense development is in hiersumnian, the Old English word for the same thing. Related: Obeyed; obeying.ETD obey (v.).2

obeisance (n.)

late 14c., obeisaunce, "act or fact of obeying, submissiveness, quality of being compliant or dutiful; respectful submission, homage," from Old French obeissance "obedience, service, feudal duty" (13c.), from obeissant, present participle of obeir "to obey," from Latin oboedire "to obey" (see obey). The sense in English altered late 14c. to "bending or prostration of the body as a gesture of submission or respect, a bow or curtsy; deferential deportment; an act of reverence or deference" by influence of abase. Related: Obeisant.ETD obeisance (n.).2

obelisk (n.)

"tapering rectangular stone column with a pyramidal apex," 1560s, from French obélisque (16c.) and directly from Latin obeliscus "obelisk, small spit," from Greek obeliskos "small spit, obelisk, leg of a compass," diminutive of obelos "a spit, pointed pillar, needle, broach; obelisk; bar of metal used as a coin or weight," a word of uncertain origin; according to Beekes, "clearly Pre-Greek." In printing, "a sign resembling a small dagger" (1580s). In dictionaries it is used to mark obsolete words. Greek obelos also was "a mark used in writing; horizontal line used as a diacritic." Related: Obeliscal; obeliskine.ETD obelisk (n.).2

Oberon

king of the faeries and husband of Titania in medieval lore, from French Obéron, from Old French Auberon, perhaps from a Germanic source related to elf. The satellite of Uranus of that name was discovered by William Herschel on Jan. 11, 1787, the same day he discovered the larger Uranian moon, Titania.ETD Oberon.2

obesity (n.)

"condition or quality of being corpulent," 1610s, from French obésité and directly from Latin obesitas "fatness, corpulence," from obesus "that has eaten itself fat," past participle of obedere "to eat all over, devour," from ob "about; because of" (see ob-) + edere "eat" (from PIE root *ed- "to eat").ETD obesity (n.).2

obese (adj.)

"exceedingly fat," 1650s, back-formation from obesity and in part from Latin obesus "fat, stout, plump," literally "that has eaten itself fat," past participle of obedere "to eat all over, devour," from ob "about; because of" (see ob-) + edere "eat" (from PIE root *ed- "to eat"). According to OED, "Rare before 19th c." Related: Obeseness. Latin obesus was translated in Old English as oferfæt "overfat." As Latin obesus also could be read as "eaten up," it also was used in a passive sense, "wasted away, lean."ETD obese (adj.).2

obfuscate (v.)

"to darken, obscure, confuse, bewilder," 1530s, from Latin obfuscatus, past participle of obfuscare "to darken" (usually in a figurative sense), from ob "in front of, before" (see ob-) + fuscare "to make dark," from fuscus "dark" (see dusk). Related: Obfuscated; obfuscating.ETD obfuscate (v.).2

obfuscation (n.)

"the act of obscuring," early 15c., obfuscacioun, originally medical, "the darkening of a sore," from Latin obfuscationem (nominative obfuscatio), noun of action from past-participle stem of obfuscare "to darken" (see obfuscate).ETD obfuscation (n.).2

Obie

one of the annual awards given to off-Broadway theater, 1967, from O.B. as the abbreviation of Off-Broadway.ETD Obie.2

obit (n.)

late 14c., "death," a sense now obsolete, from Old French obit or directly from Medieval Latin obitus "death" (a figurative use, literally "a going down, a going to a place"), noun use of past participle of Latin obire "to die," literally "to go toward" (see obituary).ETD obit (n.).2

From c. 1400 as "anniversary of a person's death; memorial service held on the anniversary of a person's death." In modern usage (since 1874) it is usually a clipped form of obituary, though it had the same meaning of "published death notice" 15c.-17c. The scholarly abbreviation ob. with date is from Latin obiit "(he) died," third person singular of obire.ETD obit (n.).3

obiter dictum

"statement in passing," a judge's expression of opinion not regarded as binding or decisive, Latin, literally "something said incidentally;" from obiter "by the way" + dictum in the legal sense "a judge's expression of opinion which is not the formal resolution of a case or determination of the court."ETD obiter dictum.2

Latin obiter is from ob "in front of, toward" (see ob-) + iter "journey" (from PIE root *ei- "to go"). Klein's sources, however, say it is ob with the suffix -iter on analogy of circiter "about" from circa. Also see obituary.ETD obiter dictum.3

obituary (n.)

1706, "register of deaths, a list of the dead," from Medieval Latin obituarius "a record of the death of a person," literally "pertaining to death," from Latin obitus "departure, a going to meet, encounter" (a euphemism for "death"), from stem of obire "go toward, go to meet" (as in mortem obire "meet death"), from ob "toward" (see ob-) + ire "to go" (from PIE root *ei- "to go").ETD obituary (n.).2

Meaning "a record or announcement of a death," especially in a newspaper, and including a brief biographical sketch, is from 1738. As an adjective, "relating to or recording a death," from 1828. A similar euphemism is in Old English cognate forðfaran "to die," literally "to go forth;" utsið "death," literally "going out, departure."ETD obituary (n.).3

obituarist (n.)

"the recorder of a death; a writer of obituaries," 1792, from obituary + -ist.ETD obituarist (n.).2

objective (adj.)

1610s, originally in the philosophical sense of "considered in relation to its object" (opposite of subjective); formed on the pattern of Medieval Latin objectivus, from objectum "object" (see object (n.)) + -ive.ETD objective (adj.).2

The meaning "impersonal, unbiased" is attested by 1855, influenced by this sense in German objektiv. Related: Objectively.ETD objective (adj.).3

object (v.)

c. 1400, objecten, "to bring forward as a ground of opposition, doubt, or criticism; raise an argument against (a proposition, line of reasoning, etc.)," from Old French objecter and directly from Latin obiectus, past participle of obiectare "to cite as grounds for disapproval, set against, oppose," literally "to put or throw before or against," frequentative of obicere (see object (n.)). Related: Objected; objecting.ETD object (v.).2

object (n.)

late 14c., "tangible thing, something perceived with or presented to the senses," from Old French object and directly from Medieval Latin obiectum "thing put before" (the mind or sight), noun use of neuter of Latin obiectus "lying before, opposite" (as a noun in classical Latin, "charges, accusations"), past participle of obicere "to present, oppose, cast in the way of," from ob "in front of, towards, against" (see ob-) + iacere "to throw" (from PIE root *ye- "to throw, impel").ETD object (n.).2

Sense of "purpose, thing aimed at" is from early 15c., from Latin obiectus "that which presents itself to the sight." Meaning "that toward which a cognitive act is directed" is from 1580s. Grammatical sense of "a member of a sentence expressing that on which the action of the verb is exerted" is from 1729.ETD object (n.).3

No object "not a thing regarded as important" is from 1782, in which the sense of object is "obstacle, hindrance" (c. 1500). As an adjective, "presented to the senses," from late 14c. Object-lesson "instruction conveyed by examination of a material object" is from 1831.ETD object (n.).4

objection (n.)

late 14c., objeccioun, "argument against the validity of a proposition or line of reasoning," from Old French objeccion "reply, retort" (12c.) and directly from Late Latin obiectionem (nominative obiectio), "a throwing or putting before" (in Medieval Latin "an objection"), noun of action from past-participle stem of Latin obicere "to oppose" (see object (n.)).ETD objection (n.).2

objectivity (n.)

1803, from Medieval Latin objectivus, from Latin objectus (see object (n.)) + -ity.ETD objectivity (n.).2

objective (n.)

1738, "something objective to the mind," from objective (adj.). Meaning "goal, aim" (1881) is from military term objective point (1852), reflecting a sense evolution in French.ETD objective (n.).2

objectification (n.)

"act or process of making or presenting (someone or something) as an object, especially an object of sense," by 1860, noun of action from objectify.ETD objectification (n.).2

objectify (v.)

"present as an object," especially as an object of sense, by 1838, from Medieval Latin obiectum (see object (n.)) + -fy. Related: Objectified; objectifying.ETD objectify (v.).2

objectionable (adj.)

"justly liable to objection, calling for disapproval," 1779, from objection + -able. Related: Objectionably.ETD objectionable (adj.).2

objectivism (n.)

1854 in philosophical sense, "the doctrine that knowledge is based on objective reality," from objective (adj.) + -ism.ETD objectivism (n.).2

objectivize (v.)

"to render objective, place before the mind as an object," 1850; see objective (adj.) + -ize. Related: Objectivized; objectivizing; objectivization (1875).ETD objectivize (v.).2

objet (n.)

"an object on display as an ornament," 1857, from French objet (14c.), especially in objet d'art, from Latin obiectus (see object (n.)). In English, objet d'art is attested from 1865.ETD objet (n.).2

objurgation (n.)

c. 1500, objurgacioun, "act of scolding or rebuking," from Old French objurgacion (15c.) and directly from Latin obiurgationem (nominative obiurgatio) "a chiding, reproving, reproof," noun of action from past-participle stem of obiurgare (see objurgate). Related: Objurgate; objurgative; objurgatory.ETD objurgation (n.).2

objurgate (v.)

"to chide, reprove," 1610s, from Latin obiurgatus, past participle of obiurgare "to chide, rebuke," from ob- (see ob-) + iurgare "to quarrel, scold," from phrase iure agere "to deal in a lawsuit," from ablative of ius "right; law; suit" (see just (adj.)) + agere "to set in motion, drive forward, do, perform," also "plead a cause at law" (from PIE root *ag- "to drive, draw out or forth, move"). Related: Objurgatory.ETD objurgate (v.).2

oblate (adj.)

"flattened on the ends," 1705, from Medieval Latin oblatus "flattened," from Latin ob "toward" (see ob-) + -latus, abstracted from its opposite, prolatus "lengthened," from lātus (adj.) "broad, wide, extensive, large," Old Latin stlatus, from PIE *stleto-, suffixed form of root *stel- "to put, stand, put in order" (source also of words meaning "to spread, to extend," such as Old Church Slavonic steljo "to spread out," Armenian lain "broad").ETD oblate (adj.).2

oblation (n.)

c. 1400, oblacioun, "an offering to a deity; a public ceremony of offering sacrifice; that which is sacrificed or solemnly offered to God," from Old French oblacion "offering, pious donation" and directly from Latin oblationem (nominative oblatio) "an offering, presenting, gift," in Late Latin "sacrifice," from Latin oblatus (see oblate (n.)). Related: Oblational; oblationary.ETD oblation (n.).2

oblate (n.)

"person devoted to religious work," especially "child dedicated by his or her parents to monastic life and raised and trained in a monastery and held in monastic discipline," 1756, from Medieval Latin oblatus, noun use of Latin oblatus, variant past participle of offerre "to offer, to bring before," from ob- (see ob-) + lātus "carried, borne," used as past participle of the irregular verb ferre "to bear."ETD oblate (n.).2

Presumably lātus was taken (by a process linguists call suppletion) from a different, pre-Latin verb. By the same process, in English, went became the past tense of go. Latin lātus is said by Watkins to be from *tlatos, from PIE root *tele- "to bear, carry" (see extol), but de Vaan says "No good etymology available."ETD oblate (n.).3

obligation (n.)

c. 1300, obligacioun, "a binding pledge, commitment to fulfill a promise or meet conditions of a bargain," from Old French obligacion "obligation, duty, responsibility" (early 13c.) and directly from Latin obligationem (nominative obligatio) "an engaging or pledging," literally "a binding" (but rarely used in this sense), noun of action from past-participle stem of obligare "to bind, bind up, bandage," figuratively "put under obligation" (see oblige). The notion is of binding with promises or by law or duty.ETD obligation (n.).2

The meaning "that which one is bound or obliged to do, especially by moral or legal claims a duty" is from c. 1600. That of "state or fact of being bound or constrained by gratitude to requite benefits, moral indebtedness," also is from c. 1600. Related: Obligational.ETD obligation (n.).3

oblige (v.)

c. 1300, obligen, "to bind by oath, put under moral or legal obligation, devote," from Old French obligier "engage one's faith, commit (oneself), pledge" (13c.), from Latin obligare "to bind, bind up, bandage," figuratively "put under obligation," from ob "to" (see ob-) + ligare "to bind," from PIE root *leig- "to tie, bind." Main modern meaning "to make (someone) indebted by conferring a benefit or kindness" is from 1560s.ETD oblige (v.).2

obliging (adj.)

of persons, dispositions, etc., "willing to do service or favors," 1630s, present-participle adjective from oblige. Related: Obligingly.ETD obliging (adj.).2

obliged (adj.)

"bound by ties of gratitude," 1540s, past-participle adjective from oblige. Earlier it meant "be in bondage, be bound by (a promise, pledge, rule, etc.)," also "be liable for the payment of; be condemned" (mid-14c.).ETD obliged (adj.).2

obligate (v.)

1540s, "to bind, fasten, connect," the literal sense of the Latin word, now obsolete in English; 1660s in the main modern sense of "to put under moral obligation;" a back-formation from obligation, or else from Latin obligatus, past participle of obligare "to bind, bind up, bandage," figuratively "put under obligation" (see oblige). Oblige, with which it has been confused since late 17c., means "to do one a favor." Related: Obligated; obligating.ETD obligate (v.).2

obligatory (adj.)

"binding in law or conscience, imposing duty, requiring performance of or forbearance from some act," c. 1400, obligatorie, from Old French obligatoire "creating an obligation, obligatory," and directly from Late Latin obligatorius "binding," from obligat-, past-participle stem of obligare "to bind, bind up, bandage," figuratively "put under obligation" (see oblige).ETD obligatory (adj.).2

obligee (n.)

in law, "person to whom another is bound by contract," 1570s, from oblige + -ee.ETD obligee (n.).2

obligor (n.)

"person who binds himself to another by contract," 1540s, agent noun in Latin form from oblige.ETD obligor (n.).2

obliquity (n.)

early 15c., obliquite, "state of being slanted or twisted; crookedness (of eyes), also figurative, "moral transgression," from Old French obliquité (14c.), from Latin obliquitatem (nominative obliquitas) "slanting direction, obliquity," noun of quality from obliquus "slanting, sidelong, indirect" (see oblique).ETD obliquity (n.).2

oblique (adj.)

early 15c., "slanting, sloping, sideways; crooked, not straight or direct," originally of muscles or eyes, from Old French oblique (14c.) and directly from Latin obliquus "slanting, sidelong, indirect," which is perhaps from ob "against" (see ob-) + root of licinus "bent upward," from a PIE root meaning "to bend, be movable," the source of see limb (n.1). But De Vaan writes, "The etymology is unknown. Closest in form and meaning are līmus 'transverse' and sublīmis 'transverse from below upward', and the latter would be morphologically similar to oblīquus. Yet a root *lī- with different suffixes *-mo- and *-kwo- does not immediately make sense, and has no clear connections outside Italic."ETD oblique (adj.).2

Figurative sense of "indirect" is from early 15c. As a noun in anatomy in reference to a type of muscle the direction of whose fibers is oblique to the long axis of the body or to the long axis of the part acted, by 1838. Related: Obliquely; obliqueness.ETD oblique (adj.).3

obliterate (v.)

"blot out, cause to disappear, remove all traces of, wipe out," c. 1600, from Latin obliteratus, past participle of obliterare "cause to disappear, blot out (a writing), erase, efface," figuratively "cause to be forgotten, blot out a remembrance," from ob "against" (see ob-) + littera (also litera) "letter, script" (see letter (n.)). The verb was abstracted from the phrase literas scribere "write across letters, strike out letters." Related: Obliterated; obliterating.ETD obliterate (v.).2

obliteration (n.)

"act of obliterating or effacing, a blotting out or wearing out, fact of being obliterated, extinction," 1650s, from Late Latin obliterationem (nominative obliteratio), noun of action from past-participle stem of obliterare "cause to disappear, blot out (a writing)," figuratively "cause to be forgotten, blot out a remembrance" (see obliterate).ETD obliteration (n.).2

oblivious (adj.)

mid-15c., "forgetful, disposed to forget, heedless," from Latin obliviosus "forgetful, that easily forgets; producing forgetfulness," from oblivio "forgetfulness, a being forgotten"(see oblivion). Meaning "unaware, unconscious (of something)" is by 1862; it formerly was regarded as erroneous, but this is now the main meaning and the word has lost its original sense of "no longer aware or mindful." Properly it should be used with to, not of. Related: Obliviously; obliviousness.ETD oblivious (adj.).2

oblivion (n.)

late 14c., oblivioun, "state or fact of forgetting, forgetfulness, loss of memory," from Old French oblivion (13c.) and directly from Latin oblivionem (nominative oblivio) "forgetfulness; a being forgotten," from oblivisci (past participle oblitus) "forget," which is of uncertain origin.ETD oblivion (n.).2

Perhaps originally "even out, smooth over, efface," from ob "over" (see ob-) + root of lēvis "smooth," but de Vaan and others find that "a semantic shift from 'to be smooth' to 'to forget' is not very convincing." However no better explanation has emerged. Latin lēvis also meant "rubbed smooth, ground down," from PIE *lehiu-, from root *(s)lei- "slime, slimy, sticky" (see slime (n.)); for sense evolution, compare obliterate.ETD oblivion (n.).3

Meaning "state or condition of being forgotten or lost to memory" is from early 15c. In English history, the Acts of Oblivion use the word in the sense of "intentional overlooking" (1610s), especially of political offenses. Related: Obliviously; obliviousness.ETD oblivion (n.).4

oblong (adj.)

"elongated, having one principal axis considerably longer than the others," early 15c., from Latin oblongus "more long than broad," originally "somewhat long," from ob "in front of; towards" here perhaps intensive (see ob-) + longus "long" (see long (adj.)). As a noun, "an oblong figure," from c. 1600.ETD oblong (adj.).2

obloquy (n.)

mid-15c., obloquie, "evil speaking, slander, calumny, derogatory remarks," from Medieval Latin obloquium "speaking against, contradiction," from Latin obloqui "to speak against, contradict," from ob "against" (see ob-) + loqui "to speak," from PIE root *tolkw- "to speak." Related: Obloquious.ETD obloquy (n.).2

obmutescence (n.)

"a keeping silent, a becoming willfully mute or obstinately speechless," 1640s, from Late Latin obmutescere "to become dumb or mute," from ob "against, before," here perhaps intensive (see ob-) + mutescere "to grow dumb," an inchoative verb formed from mutus "silent, speechless, dumb" (see mute (adj.)).ETD obmutescence (n.).2

obnoxious (adj.)

1580s, "subject to the authority of another" (a sense now obsolete), from Latin obnoxiosus "hurtful, injurious," from obnoxius "subject, exposed to harm," from ob "to, toward" (see ob-) + noxa "injury, hurt, damage entailing liability" (from PIE root *nek- (1) "death"). Meaning "subject to something harmful, exposed to injury" is by 1590s. The main modern meaning "offensive, hateful, highly objectionable" is a shifted sense recorded from 1670s, influenced by noxious.ETD obnoxious (adj.).2

Related: Obnoxiously; obnoxiousness.ETD obnoxious (adj.).3

obnubilation (n.)

"act of making dark or obscure; fact of being overclouded," c. 1600, noun of action from obnubilate (v.).ETD obnubilation (n.).2

obnubilate (v.)

"to darken, cloud, overcloud," 1580s, from Latin obnibulatus, past participle of obnubilare "to cover with clouds or fog," from ob "in front of, against" (see ob-) + verb from Latin nubes "cloud," from PIE *sneudh- "fog" (see nuance). Related: Obnubilated; obnubilating. Middle English had obnubilous "obscure, indistinct" (early 15c.).ETD obnubilate (v.).2

obo

also o.b.o., abbreviation of or best offer, by 1969 in for-sale classified ads.ETD obo.2

oboe (n.)

"wooden, double-reeded wind instrument, 1724, from Italian oboe, from phonological spelling of French hautbois (itself borrowed in English 16c. as hautboy), from haut "high, loud, high-pitched" (see haught) + bois "wood" (see bush (n.)). So called because it had the highest register among woodwind instruments. Also compare shawm. Related: Oboist (by 1830). "The tone is small, but highly individual and penetrating; it is especially useful for pastoral effects, for plaintive and wailing phrases, and for giving a reedy quality to concerted passages." [Century Dictionary]ETD oboe (n.).2

obol (n.)

ancient Greek small coin and weight, 1660s, from Latin obolus, from Greek obolos, the name of a coin (sixth part of a drachme); identical with obelos "a spit, needle, broach; bar of metal used as a coin or weight" (see obelisk). So called from the original shape. Middle English had obolus as the name of a small measure of weight, also ob "halfpenny," from Latin ob., abbreviation of obolus.ETD obol (n.).2

obreption (n.)

"the obtaining or trying to obtain something by craft or deception," 1610s, from Latin obreptionem (nominative obreptio) "a creeping or stealing on," noun of action from past-participle stem of obrepere "to creep on, creep up to," from ob "on, to" (see ob-) + repere "to creep" (see reptile). Opposed to subreption, which is to obtain something by suppression of the truth. Related: Obreptious.ETD obreption (n.).2

obscenity (n.)

1580s, "obscene quality, lewdness in action, expression, or representation," from French obscénité, from Latin obscenitatem (nominative obscenitas) "inauspiciousness, filthiness," from obscenus "offensive" (see obscene). Meaning "a foul or loathsome act" is 1610s. Sense of "an obscene utterance or word" is attested by 1690. Related: Obscenities.ETD obscenity (n.).2

obscene (adj.)

1590s, "offensive to the senses, or to taste and refinement," from French obscène (16c.), from Latin obscenus "offensive," especially to modesty, originally "boding ill, inauspicious," a word of unknown origin; perhaps from ob "in front of" (see ob-) + caenum "filth."ETD obscene (adj.).2

The meaning "offensive to modesty or decency, impure, unchaste" is attested from 1590s. Legally, "any impure or indecent publication tending to corrupt the mind and to subvert respect for decency and morality." In modern U.S. law, the definition hinged on "whether to the average person, applying contemporary community standards, the dominant theme of the material taken as a whole appeals to a prurient interest." [Justice William Brennan, "Roth v. United States," June 24, 1957]; this was refined in 1973 by "Miller v. California":ETD obscene (adj.).3

Related: Obscenely.ETD obscene (adj.).4

obscure (adj.)

c. 1400, "dark," figuratively "morally unenlightened; gloomy," from Old French obscur, oscur "dark, clouded, gloomy; dim, not clear" (12c.) and directly from Latin obscurus "dark, dusky, shady," figuratively "unknown; unintelligible; hard to discern; from insignificant ancestors," from ob "over" (see ob-) + -scurus "covered," from PIE root *(s)keu- "to cover, conceal." Related: Obscurely.ETD obscure (adj.).2

The figurative sense of "not readily understood, not manifest to the mind or understanding" is from early 15c.; of persons, "not illustrious or noted, unknown to fame," 1540s. The more literal sense of "indistinct, without clearness of form or outline, hardly perceptible, not capable of being clearly seen through lack of light" is attested in English from 1590s.ETD obscure (adj.).3

obscure (v.)

early 15c., obscuren, "to cover (something), cloud over," from obscure (adj.) or else from Old French obscurer, from Latin obscurare "to make dark, darken, obscure," from obscurus. Meaning "to conceal from knowledge or observation, disguise" is from 1520s; that of "to overshadow or outshine" is from 1540s. Related: Obscured; obscuring.ETD obscure (v.).2

obscurity (n.)

late 15c., obscurite, "absence of light, lack of brightness or luster;" 1610s with the meaning "condition of being unknown or inconspicuous;" from obscure (adj.) + -ity; or else from Old French obscurete, a variant of oscureté "darkness, gloom; vagueness, confusion; insignificance" (14c.) and directly from Latin obscuritatem (nominative obscuritas) "darkness, indistinctness, uncertainty," from obscurus. Meaning "quality or condition of not being clearly comprehended" is from late 15c. (Caxton).ETD obscurity (n.).2

obscuration (n.)

1540s, "act of darkening; state of being made dark," from Latin obscurationem (nominative obscuratio) "a darkening, obscuring," noun of action from past-participle stem of obscurare "to make dark, darken, obscure," from obscurus (see obscure (adj.) ).ETD obscuration (n.).2

obscurant (adj.)

"that obscures or darkens; that labors to prevent enlightenment," 1804, from French obscurant, from Latin obscurantem (nominative obscurans), present participle of obscurare "to make dark, darken, obscure," from obscurus (see obscure (adj.)).ETD obscurant (adj.).2

obscurantism (n.)

"opposition to the advancement and diffusion of knowledge, a desire to prevent inquiry or enlightenment," 1801, from German obscurantism, obscurantismus (by 1798); see obscurant + -ism.ETD obscurantism (n.).2

obscurantist (n.)

"one who opposes the progress of intellectual enlightenment," 1827; see obscurantism + -ist. As an adjective by 1841.ETD obscurantist (n.).2

obsecration (n.)

late 14c., obsecracioun, "prayer, earnest entreaty," especially "a prayer of supplication," from Latin obsecrationem (nominative obsecratio) "a beseeching, imploring, supplication, entreaty," noun of action from past-participle stem of obsecrare "to beseech, entreat" (on religious grounds), from ob "in front of, before" (see ob-) + sacrare "to make or declare sacred" (see sacred).ETD obsecration (n.).2

obsequy (n.)

late 14c., obsequi, in plural, "funeral rites, a funeral," from Anglo-French obsequie, Old French obseque, osseque "funeral rites" and directly from Medieval Latin obsequiae, influenced in sense by confusion of Latin obsequium "compliance" (see obsequious) with exsequiae "funeral rites." Typically in plural, obsequies.ETD obsequy (n.).2

obsequies (n.)

"funeral rites," plural of obsequy.ETD obsequies (n.).2

obsequious (adj.)

late 15c., "prompt to serve, meekly compliant with the will or wishes of another, dutiful," from Latin obsequiosus "compliant, obedient," from obsequium "compliance, dutiful service," from obsequi "to accommodate oneself to the will of another," from ob "after" (see ob-) + sequi "to follow" (from PIE root *sekw- (1) "to follow"). Pejorative sense of "fawning, sycophantic, unduly compliant" had emerged by 1590s. Related: Obsequiously; obsequiousness (mid-15c.).ETD obsequious (adj.).2

observation (n.)

late 14c., observacioun, "the performance of a religious rite," from Old French observation (c. 1200) and directly from Latin observationem (nominative observatio) "a watching over, observance, investigation," noun of action from past-participle stem of observare "watch over, note, heed, look to, attend to, guard, regard, comply with," from ob "in front of, before" (see ob-) + servare "to watch, keep safe," from PIE root *ser- (1) "to protect." Sense of "act or fact of paying attention" is from 1550s. Meaning "a remark in reference to something observed" is recorded from 1590s.ETD observation (n.).2

observance (n.)

mid-13c., observaunce, "act performed in accordance with prescribed usage," especially a religious or ceremonial one; late 14c., "care, concern, act of paying attention (to something)," from Old French observance, osservance "observance, discipline," and directly from Latin observantia "act of keeping customs, attention, respect, regard, reverence," from observantem (nominative observans), present participle of observare "watch over, note, heed, look to, attend to, guard, regard, comply with," from ob "in front of, before" (see ob-) + servare "to watch, keep safe," from PIE root *ser- (1) "to protect." Observance is the attending to and carrying out of a duty or rule. Observation is watching, noticing.ETD observance (n.).2

observe (v.)

late 14c., observen, "to hold to (a manner of life or course of conduct), carry out the dictates of, attend to in practice, to keep, follow," from Old French observer, osserver "to observe, watch over, follow" (10c.), from Latin observare "watch over, note, heed, look to, attend to, guard, regard, comply with," from ob "in front of, before" (see ob-) + servare "to watch, keep safe," from PIE root *ser- (1) "to protect." Sense of "watch, perceive, notice" is from 1560s, via the notion of "see and note omens." Meaning "to say by way of remark" is from c. 1600. Related: Observed; observing.ETD observe (v.).2

observant (adj.)

c. 1600, "attentive in perceiving or taking notice, characterized by good powers of observation," also "attentive in observing what is prescribed or required" (a law, custom, etc.), from observe + -ant, or else from French observant, past participle of observer (see observance). In reference to Judaism, "strict in acting in accordance with precepts," from 1902. As a noun from late 15c. Related: Observantly; observantness.ETD observant (adj.).2

observer (n.)

1550s, "one who keeps a rule, custom, etc.," agent noun from observe. Meaning "one who watches and takes notice" is from 1580s; this is the sense of the word in many newspaper names. Meaning "one who observes without participating" (at a meeting, conference, etc.) is by 1925.ETD observer (n.).2

observative (adj.)

"of or pertaining to observation," 1610s, from Latin observat-, past-participle stem of observare "watch over, note, heed, look to, attend to, guard, regard, comply with" (see observe) + -ive.ETD observative (adj.).2

observable (adj.)

c. 1600, "that must be attended, followed, or kept," also "worthy of notice or mention," from Latin observabilis "remarkable, observable," from observare "watch over, note, heed, look to, attend to, guard, regard, comply with," from ob "in front of, before" (see ob-) + servare "to watch, keep safe," from PIE root *ser- (1) "to protect." From 1640s as "perceptible, capable of being observed." Related: Observably; observability.ETD observable (adj.).2