aeon (n.) Look up aeon at Dictionary.com
1640s; see eon.
aerate (v.) Look up aerate at Dictionary.com
1794, from Latin aer (genitive aeris; see air (n.1)) + verbal suffix -ate (2). Related: Aerated; aerating.
aeration (n.) Look up aeration at Dictionary.com
1570s, from French aération, from aérer (v.), from Latin aer (see air (n.1)). In some cases, from aerate.
aerial (adj.) Look up aerial at Dictionary.com
c. 1600, from Latin aerius "airy, aerial, lofty, high" (from Greek aerios "of the air, pertaining to air," from aer "air;" see air (n.1)) + adjectival suffix -al (1).
aerial (n.) Look up aerial at Dictionary.com
1902 (short for aerial antenna, etc.); see aerial (adj.).
aerie (n.) Look up aerie at Dictionary.com
"eagle's nest," 1580s (attested in Anglo-Latin from early 13c.), from Old French aire "nest," Medieval Latin area "nest of a bird of prey" (12c.), perhaps from Latin area "level ground, garden bed" [Littré], though some doubt this [Klein]. Another theory connects it to atrium. Formerly misspelled eyrie (1660s) on the mistaken assumption that it derived from Middle English ey "egg."
aero- Look up aero- at Dictionary.com
word-forming element meaning "air, atmosphere; aircraft; gases," from Greek aero-, comb. form of aer (genitive aeros) "air, lower atmosphere" (see air (n.1)).
aerobatics (n.) Look up aerobatics at Dictionary.com
aircraft tricks, "trick flying," 1914, from aero- + ending from acrobat (also see -ics). Earlier (1879) it meant "the art of constructing and using airships; aerial navigation; aeronautics."
aerobic (adj.) Look up aerobic at Dictionary.com
"living only in the presence of oxygen," 1875, (after French aérobie, coined 1863 by Louis Pasteur) from Greek aero- "air" (see aero-) + bios "life" (see bio-).
aerobics (n.) Look up aerobics at Dictionary.com
method of exercise and a fad in early 1980s, American English, coined 1968 by Kenneth H. Cooper, U.S. physician, from aerobic (also see -ics) on the notion of activities which require modest oxygen intake and thus can be maintained.
aerodonetics (n.) Look up aerodonetics at Dictionary.com
science of gliding, 1907, from Greek aero- "air" (see aero-) + stem of donein "to shake, drive about." Also see -ics.
aerodrome (n.) Look up aerodrome at Dictionary.com
1902, from aero- on analogy of hippodrome. Earlier (1891) a name for a flying machine.
aerodynamic (adj.) Look up aerodynamic at Dictionary.com
also aero-dynamic, 1847; see aero- + dynamic (adj.). Compare German aerodynamische (1835), French aérodynamique.
aerodynamics (n.) Look up aerodynamics at Dictionary.com
1837, from aero- "air" + dynamics.
aerofoil (n.) Look up aerofoil at Dictionary.com
1907, from aero- + foil (n.).
aeronautics (n.) Look up aeronautics at Dictionary.com
1824, from aeronautic (1784), from French aéronautique, from aéro- (see aero-) + nautique "of ships," from Latin nauticus, from Greek nautikos (see nautical). Originally of balloons. Also see -ics. Aeronaut "balloonist" is from 1784.
aerophyte (n.) Look up aerophyte at Dictionary.com
1840, perhaps via French aerophyte, from aero- + -phyte "plant."
aeroplane (n.) Look up aeroplane at Dictionary.com
1866, from French aéroplane (1855), from Greek aero- "air" (see air (n.1)) + stem of French planer "to soar," from Latin planus "level, flat" (see plane (n.1)). Originally in reference to surfaces (such as the protective shell casings of beetles' wings); meaning "heavier than air flying machine" first attested 1873, probably an independent English coinage (see airplane).
aerosol (n.) Look up aerosol at Dictionary.com
1919, from aero- "air" + first syllable in solution. A term in physics; modern commercial application is from 1940s.
aerospace (adj.) Look up aerospace at Dictionary.com
1958, American English, from aero- "atmosphere" + (outer) space (n.).
Aeschylus Look up Aeschylus at Dictionary.com
Greek Aiskhylos (525-456 B.C.E.), Athenian soldier, poet, and playwright, Father of Tragedy.
Aesir (n.) Look up Aesir at Dictionary.com
chief gods of Scandinavian religion, from Old Norse plural of ass "god," from Proto-Germanic *ansu- (source also of Old High German ansi, Old English os, Gothic ans "god"), from PIE *ansu- "spirit" (source also of first element in Avestan Ahura Mazda).
Aesop Look up Aesop at Dictionary.com
Greek Aisopos, semi-legendary 6c. B.C.E. fablist.
Aesopic (adj.) Look up Aesopic at Dictionary.com
1927, in the context of Soviet literary censorship, in reference to writing "obscure or ambiguous, often allegorical, which disguises dissent," from Aesop, the traditional father of the allegorical fable, + -ic. The term (Russian ezopovskii, 1875) arose under the Tsars. The style was used by Russian communists, who, once they took power, used the word in charges against their own dissidents.
aesthete (n.) Look up aesthete at Dictionary.com
attested from 1878, in vogue 1881, from Greek aisthetes "one who perceives," from stem of aisthanesthai "to perceive, to feel" (see aesthetic). Or perhaps from aesthetic on the model of athlete/athletic.
1. Properly, one who cultivates the sense of the beautiful; one in whom the artistic sense or faculty is highly developed; one very sensible of the beauties of nature or art.--2. Commonly, a person who affects great love of art, music, poetry, and the like, and corresponding indifference to practical matters; one who carries the cultivation of subordinate forms of the beautiful to an exaggerated extent: used in slight contempt. [Century Dictionary, 1897]

I want to be an aesthete,
And with the aesthetes stand;
A sunflower on my forehead,
And a lily in my hand.

["Puck," Oct. 5, 1881]
aesthetic (n.) Look up aesthetic at Dictionary.com
1798, from German Ästhetisch or French esthétique, both from Greek aisthetikos "sensitive, perceptive," from aisthanesthai "to perceive (by the senses or by the mind), to feel," from PIE *awis-dh-yo-, from root *au- "to perceive" (see audience).

Popularized in English by translations of works of Immanuel Kant and used originally in the classically correct sense "the science which treats of the conditions of sensuous perception." Kant had tried to correct the term after Alexander Baumgarten had taken it in German to mean "criticism of taste" (1750s), but Baumgarten's sense attained popularity in English c. 1830s (despite scholarly resistance) and removed the word from any philosophical base. Walter Pater used it (1868) to describe the late 19c. movement that advocated "art for art's sake," which further blurred the sense. As an adjective by 1803. Related: Aesthetically.
aestheticism (n.) Look up aestheticism at Dictionary.com
1855, from aesthetic + -ism.
aesthetics (n.) Look up aesthetics at Dictionary.com
1803, from aesthetic (also see -ics).
aet. Look up aet. at Dictionary.com
"aged (some number of years)," abbreviation of Latin aetatis "of the age of," genitive singular of aetas "age" (see age (n.)).
aetio- Look up aetio- at Dictionary.com
word-forming element used in chemistry and indicating "a fundamental degradation product of a complex organic compound" [Flood], from Latinized comb. form of Greek aitia "a cause, an origin" (see etiology).
afanc (n.) Look up afanc at Dictionary.com
cattle-devouring aquatic monster in Celtic countries, from Celtic *abankos "water-creature," from *ab- "water" (source also of Welsh afon, Breton aven "river," Latin amnis "stream, river," which is believed to be of Italo-Celtic origin), from PIE root *ap- (2) "water" (for which see water (n.1)).
afar (adv.) Look up afar at Dictionary.com
contraction of Middle English of feor (late 12c.), on ferr (c. 1300), from Old English feor "far" (see far); the a- (1) in compounds representing both of and on (which in this use meant the same thing). Spelled afer in 14c.
afeared (adj.) Look up afeared at Dictionary.com
Old English afæred, past participle of now-obsolete afear (Old English afæran) "to terrify," from a- (1) + færan (see fear (v.)). Used frequently by Shakespeare, but supplanted in literary English after 1700 by afraid (q.v.). It still survives in popular and colloquial speech.
affability (n.) Look up affability at Dictionary.com
late 15c., from Old French affabilité (14c.), noun of quality from affable (see affable).
affable (adj.) Look up affable at Dictionary.com
late 15c., from Old French afable (14c.), from Latin affabilis "approachable, courteous, kind, friendly," literally "who can be (easily) spoken to," from affari "to speak to," from ad- "to" (see ad-) + fari "to speak," from PIE root *bha- (2) "to speak, tell, say" (see fame (n.)). Related: Affably.
affair (n.) Look up affair at Dictionary.com
c. 1300, "what one has to do," from Anglo-French afere, Old French afaire "business, event; rank, estate" (12c., Modern French affaire), from the infinitive phrase à faire "to do," from Latin ad "to" (see ad-) + facere "to do, make" (see factitious).

A Northern word originally, brought into general use and given a French spelling by Caxton (15c.). General sense of "vague proceedings" (in romance, war, etc.) first attested 1702. Meaning "an affair of the heart; a passionate episode" is from French affaire de coeur (itself attested in English from 1809); to have an affair with someone in this sense is by 1726, earlier have an affair of love:
'Tis manifeſtly contrary to the Law of Nature, that one Woman ſhould cohabit or have an Affair of Love with more than one Man at the ſame time. ["Pufendorf's Law of Nature and Nations," transl. J. Spavan, London, 1716]

Thus, in our dialect, a vicious man is a man of pleasure, a sharper is one that plays the whole game, a lady is said to have an affair, a gentleman to be a gallant, a rogue in business to be one that knows the world. By this means, we have no such things as sots, debauchees, whores, rogues, or the like, in the beau monde, who may enjoy their vices without incurring disagreeable appellations. [George Berkeley, "Alciphron or the Minute Philosopher," 1732]
affairs (n.) Look up affairs at Dictionary.com
"ordinary business," late 15c., plural of affair (n.).
affect (n.) Look up affect at Dictionary.com
late 14c., "mental state," from Latin noun use of affectus "furnished, supplied, endowed," figuratively "disposed, constituted, inclined," past participle of afficere "to do; treat, use, manage, handle; act on; have influence on, do something to," a verb of broad meaning, from ad- "to" (see ad-) + facere (past participle factus) "to make, do" (see factitious). Perhaps obsolete except in psychology. Related: Affects.
affect (v.2) Look up affect at Dictionary.com
"to make a pretense of," 1660s, earlier "to assume the character of (someone)," 1590s; originally in English "to aim at, aspire to, desire" (early 15c.), from Middle French affecter (15c.), from Latin affectare "to strive after, aim at," frequentative of afficere (past participle affectus) "to do something to, act on" (see affect (n.)). Related: Affected; affecting.
affect (v.1) Look up affect at Dictionary.com
"to make an impression on," 1630s; earlier "to attack" (c. 1600), "act upon, infect" (early 15c.), from affect (n.). Related: Affected; affecting.
affectation (n.) Look up affectation at Dictionary.com
"studied display," 1540s, from French affectation (16c.) or directly from Latin affectationem (nominative affectatio) "a striving after, a claiming," noun of action from past participle stem of affectare "to strive for" (see affect (v.2)).
affected (adj.) Look up affected at Dictionary.com
past participle adjective from affect (v.2); 1530s in the now-obsolete sense "favorably disposed" (preserved in disaffected); meaning "artificially displayed" is recorded from 1580s.
affection (n.) Look up affection at Dictionary.com
early 13c., "an emotion of the mind, passion, lust as opposed to reason," from Old French afection (12c.) "emotion, inclination, disposition; love, attraction, enthusiasm," from Latin affectionem (nominative affectio) "a relation, disposition; a temporary state; a frame, constitution," noun of state from past participle stem of afficere "to do something to, act on" (see affect (n.)). Sense developed from "disposition" to "good disposition toward" (late 14c.). Related: Affections.
affectionate (adj.) Look up affectionate at Dictionary.com
1580s, "fond, loving," from affection + -ate (1). Early, now mostly obsolete, senses included "inclined" (1530s), "prejudiced" (1530s), "passionate" (1540s), "earnest" (c. 1600). Other forms also used in the main modern sense of the word included affectious (1580s), affectuous (mid-15c.).
affectionately (adv.) Look up affectionately at Dictionary.com
1580s, from affectionate + -ly (2).
affiance (v.) Look up affiance at Dictionary.com
1520s, "to promise," from Old French afiancier "to pledge, promise, give one's word," from afiance (n.) "confidence, trust," from afier "to trust," from Late Latin affidare, from ad- "to" (see ad-) + fidare "to trust," from fidus "faithful" from the same root as fides "faith" (see faith). From mid-16c. especially "to promise in marriage." Related: Affianced; affiancing.
affidavit (n.) Look up affidavit at Dictionary.com
1590s, from Medieval Latin affidavit, literally "he has stated on oath," third person singular perfective of affidare "to trust," from Latin ad- "to" (see ad-) + fidare "to trust," from fidus "faithful," from the same root as fides "faith" (see faith). So called from being the first word of sworn statements.
affiliate (v.) Look up affiliate at Dictionary.com
1761, from Latin affiliatus, past participle of affiliare "to adopt" (see affiliation). Outside legal use, always figurative. Related: Affiliated; affiliating.
affiliate (adj.) Look up affiliate at Dictionary.com
1858, from affiliate (v.).
affiliate (n.) Look up affiliate at Dictionary.com
1846, from affiliate (v.).