adversary (n.) Look up adversary at Dictionary.com
mid-14c., aduersere, from Anglo-French adverser (13c.), Old French adversaire "adversary, opponent, enemy," or directly from Latin adversarius "opponent, adversary, rival," noun use of adjective meaning "opposite, hostile, contrary," literally "turned toward one," from adversus "turned against" (see adverse). The Latin word is glossed in Old English by wiðerbroca.
adverse (adj.) Look up adverse at Dictionary.com
late 14c., "contrary, opposing," from Old French avers (13c., Modern French adverse) "antagonistic, unfriendly, contrary, foreign" (as in gent avers "infidel race"), from Latin adversus "turned against, turned toward, fronting, facing," figuratively "hostile, adverse, unfavorable," past participle of advertere, from ad- "to" (see ad-) + vertere "to turn" (see versus). Related: Adversely.
adversity (n.) Look up adversity at Dictionary.com
c.1200, aduersite "misfortune, hardship, difficulty," from Old French aversité "adversity, calamity, misfortune; hostility, wickedness, malice" (Modern French adversité), from Latin adversitatem (nominative adversitas) "opposition," from adversus (see adverse).
advert (n.) Look up advert at Dictionary.com
colloquial shortening of advertisement, attested by 1860.
advert (v.) Look up advert at Dictionary.com
mid-15c., averten "to turn (something) aside," from Middle French avertir (12c.), from Late Latin advertere (see advertise). The -d- added 16c. on the Latin model. Related: Adverted; adverting.
advertise (v.) Look up advertise at Dictionary.com
early 15c., "to take notice of," from Middle French advertiss-, present participle stem of a(d)vertir "to warn" (12c.), from Latin advertere "turn toward," from ad- "toward" (see ad-) + vertere "to turn" (see versus).

Sense shifted to "to give notice to others, warn" (late 15c.) by influence of advertisement; specific meaning "to call attention to goods for sale, rewards, etc." had emerged by late 18c. Original meaning remains in the verb advert "to give attention to." Related: Advertised; advertising.
advertised (adj.) Look up advertised at Dictionary.com
late 15c., "informed;" 1780s, "publicly announced," past participle adjective from advertise.
advertisement (n.) Look up advertisement at Dictionary.com
early 15c., "written statement calling attention to" something, "public notice" (of anything, but often of a sale); from Middle French avertissement, from stem of avertir (see advertise). Meaning "public notice" (usually paid), the main modern sense, emerged 1580s and was fully developed by 18c.
advertiser (n.) Look up advertiser at Dictionary.com
1560s, agent noun from advertise (v.).
advice (n.) Look up advice at Dictionary.com
late 13c., auys "opinion," from Old French avis "opinion, view, judgment, idea" (13c.), from phrase ço m'est à vis "it seems to me," or from Vulgar Latin *mi est visum "in my view," ultimately from Latin visum, neuter past participle of videre "to see" (see vision).

The unhistorical -d- was introduced in English 15c., on model of Latin words in ad-. Substitution of -c- for -s- is 18c., to preserve the breath sound and to distinguish from advise. Meaning "opinion given as to action, counsel" is from late 14c.
advisability (n.) Look up advisability at Dictionary.com
1778 (in a letter from George Washington at Valley Forge), from advisable + -ity.
advisable (adj.) Look up advisable at Dictionary.com
1640s, from advise (v.) + -able.
advise (v.) Look up advise at Dictionary.com
late 13c., avisen "to view, consider," from Old French aviser "deliberate, reflect, consider" (13c.), from avis "opinion" (see advice). Meaning "to give counsel to" is late 14c. Related: Advised; advising.
advisement (n.) Look up advisement at Dictionary.com
early 14c., avisement "examination, inspection, observation," from Old French avisement "consideration, reflection," from aviser (see advise). Meaning "advice, counsel" is from c.1400, as is that of "consultation, conference."
adviser (n.) Look up adviser at Dictionary.com
1610s, agent noun from advise (v.). Meaning "military person sent to help a government or army in a foreign country" is recorded from 1915. Alternative form, Latinate advisor, is perhaps a back-formation from advisory.
advisory (adj.) Look up advisory at Dictionary.com
1778; see advise + -ory. The noun meaning "weather warning" is from 1931.
advocacy (n.) Look up advocacy at Dictionary.com
late 14c., from Old French avocacie (14c.), from Medieval Latin advocatia, noun of state from Latin advocatus (see advocate (n.)).
advocate (n.) Look up advocate at Dictionary.com
mid-14c., "one whose profession is to plead cases in a court of justice," a technical term from Roman law, from Old French avocat "barrister, advocate, spokesman," from Latin advocatus "one called to aid; a pleader, advocate," noun use of past participle of advocare "to call" (as witness or advisor) from ad- "to" (see ad-) + vocare "to call," related to vocem (see voice (n.)). Also in Middle English as "one who intercedes for another," and "protector, champion, patron." Feminine forms advocatess, advocatrice were in use in 15c.
advocate (v.) Look up advocate at Dictionary.com
1640s, from advocate (n.). Related: Advocated; advocating; advocation.
adware (n.) Look up adware at Dictionary.com
2000 (earlier as the name of a software company), from ad (n.) + -ware, abstracted from software, etc.
adze (n.) Look up adze at Dictionary.com
also adz, Middle English adese, adse, from Old English adesa "adze, hatchet," of unknown origin, perhaps somehow related to Old French aisse, Latin ascia "axe" (see ax). Spelling with -z- is from 18c. Adze "has been monosyllabic only since the seventeenth century. The word has no cognates, though it resembles the names of the adz and the hammer in many languages" [Liberman, 2008].
ae Look up ae at Dictionary.com
see æ. As a word, it can represent Old English æ "law," especially law of nature or God's law; hence "legal custom, marriage."
Aegean Look up Aegean at Dictionary.com
sea between Greece and Asia Minor, 1570s, traditionally named for Aegeus, father of Theseus, who threw himself to his death in it when he thought his son had perished; but perhaps from Greek aiges "waves," a word of unknown origin.
aegis (n.) Look up aegis at Dictionary.com
"protection," 1793, from Latin aegis, from Greek Aigis, the name of the shield of Zeus, said by Herodotus to be related to aix (genitive aigos) "goat," from PIE *aig- "goat" (cognates: Sanskrit ajah, Lithuanian ozys "he-goat"), as the shield was of goatskin. Athene's aigis was a short goat-skin cloak, covered with scales, set with a gorgon's head, and fringed with snakes. The exact use and purpose of it is not now clear.
The goatskin would be worn with the two forelegs tied in front of the wearer's breast, or possibly with the head passed through an opening made at the neck, by the removal of the animal's head. [F. Warre Cornish, ed., "Dictionary of Greek and Roman Antiquities," London, 1898]
aegrotat (n.) Look up aegrotat at Dictionary.com
certificate that a student is ill, Latin, literally "he is sick," third person singular of aegrotare "to be sick," from aeger "sick."
Aeneas Look up Aeneas at Dictionary.com
hero of the "Æneid," son of Anchises and Aphrodite, Latin, from Greek Aineias, of unknown origin, perhaps literally "praise-worthy," from ainos "tale, story, saying, praise" (related to enigma); or perhaps related to ainos "horrible, terrible." The Aeneid (late 15c. in English) is literally "of or pertaining to Aeneas," from French Enéide, Latin Æneida.
Aeolian (adj.) Look up Aeolian at Dictionary.com
c.1600, "of the wind," from Latin Æolus "god of the winds," from Greek Aiolos, from aiolos "quickly moving." Æolian harp first recorded 1791. The ancient district of Aiolis in Asia Minor was said to have been named for the wind god, hence Æolian also refers to one branch of the ancient Greek people.
Aeolus Look up Aeolus at Dictionary.com
see Aeolian.
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, Athenian soldier, poet, and playwright, Father of Tragedy (525-456 B.C.E.).
Aesir (n.) Look up Aesir at Dictionary.com
chief gods of Scandinavian religion, from Old Norse plural of ass "god," related to Old English os, Gothic ans "god" (see Asgard).