antivirus (n.)
1903, from anti- + virus.
antler (n.)
late 14c., "first tine or branch of the horns of a deer," from Anglo-French auntiler, Old French antoillier (14c., Modern French andouiller) "antler," which is perhaps from Gallo-Roman cornu *antoculare "horn in front of the eyes," from Latin ante "before" (from PIE root *ant- "front, forehead," with derivatives meaning "in front of, before") + ocularis "of the eyes" (from Latin oculus "an eye," from PIE root *okw- "to see").

This etymology is doubted by some because no similar word exists in any other Romance language, but compare German Augensprossen "antlers," literally "eye-sprouts," for a similar formation. Later used of any branch of the horns. Related: Antlered (1813).
antoecian (adj.)
"pertaining to the people dwelling on the opposite side of the earth," 1860, from antoeci (plural) "people dwelling on the opposite side of the earth" (1620s), a Latinized form of Greek antoikoi, literally "dwellers opposite," from anti "opposite" (see anti-) + oikein "to dwell" (from PIE root *weik- (1) "clan").
Antonia
fem. proper name, from Latin Antonia, fem. of Antonius (see Anthony).
Antonine (adj.)
1680s, in reference to Roman emperors Antoninus Pius (ruled 138-161 C.E.) and Marcus Aurelius Antoninus (161-180). For the name, see Anthony. Earlier (1540s) of the followers of St. Anthony of Egypt; later Antonian (1904) was used in this sense.
antonomasia (n.)
rhetorical substitution of an epithet for a proper name (or vice versa; as in His Holiness for the name of a pope), 1580s, from Latin, from Greek antonomasia, from antonomazein "to name instead, call by a new name," from anti "instead" (see anti-) + onomazein "to name," from onoma "name" (see name (n.)). Related: Antonomastic.
Antony
masc. proper name, from Latin Antonius, name of a Roman gens (see Anthony).
antonym (n.)
"an antithetical word," 1867, coined to serve as opposite of synonym, from Greek anti "opposite, against" (see anti-) + onym "name" (see name (n.)). Perhaps introduced to English in the book "Synonyms and Antonyms" (1867) by the Ven. C.J. Smith, M.A.
UNDER the head of Synonyms and Antonyms, Archdeacon Smith arranges words which form an antithesis to one another. The word "antonym" is, we believe, a new formation but useful. ["Journal of Sacred Literature," July 1867]
French antonyme (1842), German antonym (by 1859) are older. The un-Greek alternative counterterm has been left to fade.
antrum (n.)
"a cave or cavity of the body," 1727, medical Latin, from Greek antron "a cave," a word of uncertain etymology, perhaps from a pre-Greek substrate language. Related: Antral.
antsy (adj.)
"restlessly impatient," 1838, American English, from plural of ant + -y (2); probably reflecting the same image as the slang expression have ants in (one's) pants "be restless and fidgety" from a century later. Related: Antsiness.
Antwerp
port city in Belgium, French Anvers, from a Germanic compound of *anda "at" + *werpum "wharf" (see wharf). Folk etymology connects the first word with hand.
Anubis
jackal-headed god of Egyptian religion, identified by the later Greeks with their Hermes, from Greek Anoubis, from Egyptian Anpu, Anepu.
anuria (n.)
"absence of urination," 1838, medical Latin, from Greek an- "not, without" (see an- (1)) + ouron "urine" (see urine) + abstract noun ending -ia.
anus (n.)
"inferior opening of the alimentary canal," 1650s, from Old French anus, from Latin anus "ring, anus," from PIE root *āno- "ring." So called for its shape; compare Greek daktylios "anus," literally "ring (for the finger)," from daktylos "finger."
anvil (n.)
Old English anfilt "anvil," a Proto-Germanic compound (cognates: Middle Dutch anvilt, Old High German anafalz, Dutch aanbeeld, Danish ambolt "anvil"), apparently representing *ana- "on" (see on (prep.)) + *filtan "to hit" (from PIE root *pel- (5) "to thrust, strike, drive").

The ear bone (incus) is so called from 1680s. Anvil Chorus is based on the "Gypsy Song" that opens Act II of Giuseppe Verdi's opera "Il Trovatore," first performed in Teatro Apollo, Rome, Jan. 19, 1853.
anxiety (n.)
1520s, "apprehension caused by danger, misfortune, or error, uneasiness of mind respecting some uncertainty," from Latin anxietatem (nominative anxietas) "anguish, anxiety, solicitude," noun of quality from anxius "uneasy, troubled in mind" (see anxious).

Sometimes considered a pathological condition (1660s); psychiatric use dates to 1904. Age of Anxiety is from Auden's poem (1947). For "anxiety, distress," Old English had angsumnes, Middle English anxumnesse.
anxious (adj.)
1620s, "greatly troubled by uncertainties," from Latin anxius "solicitous, uneasy, troubled in mind" (also "causing anxiety, troublesome"), from angere, anguere "to choke, squeeze," figuratively "to torment, cause distress" (from PIE root *angh- "tight, painfully constricted, painful"). The same image is in Serbo-Croatian tjeskoba "anxiety," literally "tightness, narrowness." Meaning "earnestly desirous" (as in anxious to please) is from 1742. Related: Anxiously; anxiousness.
any (adj., pron.)
"one, a or an, some," Old English ænig (adjective, pronoun) "any, anyone," literally "one-y," from Proto-Germanic *ainagas (source also of Old Saxon enig, Old Norse einigr, Old Frisian enich, Dutch enig, German einig), from PIE root *oi-no- "one, unique." The -y may have diminutive force here.

As a noun, late 12c.; as an adverb, "in any degree," c. 1400. Emphatic form any old ______ (British variant: any bloody ______) is recorded from 1896. At any rate is recorded from 1847. Among the large family of compounds beginning with any-, anykyn "any kind" (c. 1300) did not survive, and Anywhen (1831) is rarely used, but OED calls it "common in Southern [English] dialects."
[A]ani refers to single entities, amounts, etc., occurring at random or chosen at random, as being convenient, suitable, to one's liking, etc. It is frequently emphatic and generalizing, having the force of 'any whatever, any at all' and 'any and every'. It is common in questions, conditional clauses, and negative statements, but not in affirmative statements (where som is used instead). [Middle English Dictionary]
anybody (n.)
c. 1300, ani-bodi, "any person," from any + body. One-word form attested by 1826. Phrase anybody's game (or race, etc.) is from 1840.
anyhow (adv.)
1740, "in any way or manner," from any + how (adv.). Unlike most other any + (interrogative) compounds, there is no record of it in Old or Middle English. Compare anyway (16c.). Also used as a conjunction, "in any case." Emphatic form any old how is recorded from 1900, American English.
anymore (adv.)
one-word form by 1865, from any + more. Typically used with a negative, a custom as old as Middle English, where without any more is found late 14c.
anyone (n.)
"any person or persons," 1844 as one word; since Old English as two words, from any + one. Old English also used ænigmon in this sense, Middle English eani mon, ani on; also compare anybody.
anyplace (n.)
1911 as one word; two-word form is in Middle English (late 14c.); from any + place (n.).
anything (n.)
"a thing," indefinitely, late Old English aniþing, from any + thing. But Old English ænig þinga apparently also meant "somehow, anyhow" (glossing Latin quoquo modo).
anythingarian (n.)
"one indifferent to religious creeds, one 'that always make their interest the standard of their religion,'" 1704, originally dismissive, from anything on model of trinitarian, unitarian, etc.
anytime (adv.)
one-word form by 1854; two-word form is in Middle English (early 15c.; any while in the same sense is late 14c.), from any + time (n.).
anyway (adv.)
one-word form is common from 1830s; in two words from 1560s, "in any manner," also any ways (with adverbial genitive); see any + way (n.). As an adverbial conjunction, from 1859.

Middle English in this sense had ani-gates "in any way, somehow" (c. 1400), also on anikinnes wise "in any way or manner" (c. 1200), and Late Old English had on enige wisan "in any wise, in any manner." As a prepositional phrase, in any way is from late 14c.
anyways (adv.)
16c., anyway (q.v.) with adverbial genitive -s.
anywhere (adv.)
"in, at, or to any place," late 14c., from any + where. Earlier words in this sense were owhere, oughwhere, aywhere, literally "aught where" (see aught (n.1)).
anywhither (adv.)
"in any direction," 1610s, from any + whither.
anywise (adv.)
"to any degree, in any way," c. 1200, from Old English ænige wisan, from any + wise (n.).
Anzac
1915, acronym of Australian and New Zealand Army Corps. First used in reference to the Gallipoli campaign.
AOL
dominant online service of the late 1990s, initialism (acronym) of America Online, a company name attested from late 1989.
aorist (n.)
1580s, the tense of Greek verbs that most closely corresponds to the simple past in English, from Greek aoristos (khronos) "indefinite (tense)," from aoristos "without boundaries, undefined, indefinite," from assimilated form of a- "not" (see a- (3)) + horistos "limited, defined," verbal adjective from horizein "to limit, define," from horos "boundary, limit, border" (see horizon). Related: Aoristic.
aorta (n.)
in anatomy, "main trunk of the arterial system," 1590s, from Medieval Latin aorta, from Greek aorte "a strap to hang (something by)," a word applied by Aristotle to the great artery of the heart, literally "what is hung up," probably from aeirein "to lift, heave, raise," which is of uncertain origin, possibly from PIE root *wer- (1) "raise, lift, hold suspended." Used earlier by Hippocrates of the bronchial tubes. It is cognate with the second element in meteor. Related: Aortal; aortic.
AP
abbreviation of Associated Press, first recorded 1879; the organization was founded May 1848 as co-operative news gathering effort among New York City newspaper publishers covering the war with Mexico.
ap- (2)
patronymic element in Welsh pedigrees and names, earlier map "son," cognate with Gaelic mac. Since 17c. merged into surnames and reduced to P- or B- (Ap Rhys = Price, Ap Evan = Bevan, Bowen = Ap Owen, etc.).
It is said that a Welshman who evidently was not willing to be surpassed in length of pedigree, when making out his genealogical tree, wrote near the middle of his long array of 'aps' -- "about this time Adam was born." ["Origin and Significance of our Names," "The Chautauquan," Oct. 1887-July 1888]
ap- (1)
form of Latin ad- in compounds with words or stems beginning in -p-; see ad-. In Old French reduced to a-, but scribal re-doubling of ap- to app- in imitation of Latin began 14c. in France, 15c. in England, and was extended to some compounds formed in Old French or Middle English that never had a Latin original (appoint, appall).

In words from Greek, ap- is the form of apo before a vowel (see apo-).
apace (adv.)
late 14c. contraction of a pace (early 14c.), literally "at a pace," but usually with a sense of "at a good pace," from a- (1) "on" + pace (n.).
Apache
1745, from American Spanish (where it is attested by 1598), probably from Yavapai (a Yuman language) 'epache "people." Sometimes derived from Zuni apachu "enemy" (see F.W. Hodge, "American Indians," 1907), but this seems to have been the Zuni name for the Navajo.

French journalistic sense of "Parisian gangster or thug" first attested 1902; Apache dance was the World War I-era equivalent of 1990s' brutal "slam dancing." Fenimore Cooper's Indian novels were enormously popular in Europe throughout the 19c., and comparisons of Cooper's fictional Indian ways in the wilderness and underworld life in European cities go back to Dumas' "Les Mohicans de Paris" (1854-1859). It is probably due to the imitations of Cooper (amounting almost to plagiarisms) by German author Karl May (1842-1912) that Apaches replaced Mohicans as the quintessential savages in European popular imagination. Also compare Mohawk.
apagoge (n.)
"demonstration of a proposition by the refutation of its opposite, indirect proof, reductio ad absurdum," from Greek apagoge "a leading away" (used by Aristotle in a logical sense), from apagein "to lead away," from assimilated form of apo "from, away from" (see apo-) + agein "push forward, put in motion; stir up; excite, urge," from PIE root *ag- "to drive, draw out or forth, move." Related: Apogogic (1670s); apogogical.
apanage (n.)
see appanage.
apanthropy (n.)
"aversion to human company, love of solitude," 1753, nativized form of Greek apanthropia, abstract noun from apanthropos "unsocial," from assimilated form of apo "off, away from" (see apo-) + anthropos "man, human" (see anthropo-). Related: Apanthropic.
apart (adv.)
"to or at the side; by itself, away from others," late 14c., from Old French a part (Modern French à part) "to the side," from Latin ad "to" (see ad-) + partem, accusative of pars "a part, piece, a faction, a part of the body" (from PIE root *pere- (2) "to grant, allot"). The first element is probably felt in English as a- as in abroad, ahead (see a- (1)). As an adjective from 1786.
apartheid (n.)
1947 (the policy was officially begun 1948), "segregation of European from non-European people," from Afrikaans apartheid (1929 in a South African socio-political context), literally "separateness," from Dutch apart "separate" (from French àpart; see apart) + suffix -heid, which is cognate with English -hood. The official English synonym was separate development (1955).
"Segregation" is such an active word that it suggests someone is trying to segregate someone else. So the word "apartheid" was introduced. Now it has such a stench in the nostrils of the world, they are referring to "autogenous development." [Alan Paton, "New York Times," Oct. 24, 1960]
apartment (n.)
1640s, "private rooms for the use of one person or family within a house," from French appartement (16c.), from Italian appartimento, literally "a separated place," from appartere "to separate," from a "to" (see ad-) + parte "side, place," from Latin partem (nominative pars) "a part, piece, a division" (from PIE root *pere- (2) "to grant, allot").

Sense of "set of private rooms rented for independent living in a building entirely of these" (the U.S. equivalent of British flat) is by 1863, with reference to Paris. Apartment house is attested from 1870.
apartness (n.)
1849, from apart + -ness.
apathetic (adj.)
"characterized by apathy," 1744, apathetick, from apathy + -ic, on model of pathetic.
apathy (n.)
c. 1600, "freedom from suffering, passionless existence," from French apathie (16c.), from Latin apathia, from Greek apatheia "freedom from suffering, impassibility, want of sensation," from apathes "without feeling, without suffering or having suffered," from a- "without" (see a- (3)) + pathos "emotion, feeling, suffering" (from PIE root *kwent(h)- "to suffer"). Originally a positive quality; sense of "indolence of mind, indifference to what should excite" is by 1733.
APB
also a.p.b., "general alarm," 1960, police jargon initialism (acronym) for all-points bulletin, itself attested by 1953 (perhaps more in the jargon of detective novels than in actual police use). The notion is "information of general importance," broadcast to all who can hear it.