advice (n.)
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" (from PIE root *weid- "to see").

Meaning "opinion offered as worthy to be followed, counsel" is from late 14c. The unetymological -d- (on model of Latin words in ad-) was inserted occasionally in French by scribes 14c.-16c. and was made regular in English 15c. by Caxton. Substitution of -c- for -s- is 18c., to preserve the breath sound and to distinguish from advise.
advisability (n.)
1778 (in a letter from George Washington at Valley Forge), from advisable + -ity. Advisableness is from 1731.
advisable (adj.)
1640s, "prudent, expedient," from advise (v.) + -able (q.v.). It also can mean "open to advice" (1660s), but this is rare.
advise (v.)
late 13c., avisen "to view, consider" (a sense now obsolete); late 14c., "to give counsel to," from Old French aviser "deliberate, reflect, consider" (13c.), from avis "opinion," 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" (from PIE root *weid- "to see"). The unetymological -d- is from 16c. Related: Advised; advising.
advisement (n.)
early 14c., avisement "examination, inspection, observation," from Old French avisement "consideration, reflection; counsel, advice," from aviser "deliberate, reflect, consider," from avis "opinion" (see advice). Meaning "advice, counsel" is from c. 1400, as is that of "consultation, conference," now obsolete except in legalese phrase under advisement. The unetymological -d- is a 16c. scribal overcorrection.
adviser (n.)
1610s, "one who gives advice," agent noun from advise (v.). Meaning "faculty assigned to mentor students" is from 1887. 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.)
1778, "having the power to advise;" see advise + -ory. The noun meaning "weather warning" is from 1936, used by U.S. agencies, probably short for advisory bulletin.
advocacy (n.)
"the act of pleading for, supporting, or recommending," late 14c., from Old French avocacie "profession of an avocat" (14c.), from Medieval Latin advocatia, abstract noun from Latin advocat-, stem of advocare "to call, summon, invite" (see advocate (n.)).
advocate (v.)
"plead in favor of," 1640s, from advocate (n.) or from Latin advocatus, past participle of advocare. Related: Advocated; advocating.
advocate (n.)
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 (another); a pleader (on one's behalf), advocate," noun use of past participle of advocare "to call (as witness or adviser), summon, invite; call to aid; invoke," from ad "to" (see ad-) + vocare "to call" (from PIE root *wekw- "to speak").

Also in Middle English as "one who intercedes for another," and "protector, champion, patron." Feminine forms advocatess, advocatrice were in use in 15c.; advocatrix is from 17c.
advocation (n.)
"a calling in of legal assistance," 1520s, from Latin advocationem (nominative advocatio) "a calling or summoning of legal assistance," in Medieval Latin "duty of defense or protection," noun of action from past participle stem of advocare "to call, summon, invite; call to aid" (see advocate (n.)).
advowson (n.)
c. 1300, "right of presentation to an ancient benefice," from Anglo-French advouison, Old French avoeson, from Latin advocationem (see advocation).
adware (n.)
2000 (earlier as the name of a software company), from ad (n.) + -ware, abstracted from software, etc.
adze (n.)
also adz, "cutting tool used for dressing timber, resembling an axe but with a curved blade at a right-angle to the handle," 18c. spelling modification of ads, addes, from Middle English adese, adse, from Old English adesa "adze, hatchet," which is of unknown origin. 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]. Perhaps somehow related to Old French aisse, Latin ascia "axe" (see axe).
ae
see æ. As a word, it can represent Old English æ "law," especially law of nature or God's law; hence "legal custom, marriage" (cognate with Old High German ewa, Old Saxon eo), according to Buck probably literally "way, manner, custom," from PIE *ei- "to go."
AEF
also A.E.F., abbreviation of American Expeditionary Force, the U.S. military force sent to Europe in 1917 during World War I.
Aegean
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.
Aegina
island in the Saronic Gulf, Latinized form of Greek Aigina, which also was the name of a nymph beloved by Zeus. Related: Aeginetan.
aegis (n.)
"protection," 1793, a figurative use of Latin aegis, from Greek Aigis, the name of the shield of Zeus, a word said by Herodotus to be related to aix (genitive aigos) "goat," from PIE *aig- "goat" (source also of Sanskrit ajah, Lithuanian ozys "he-goat"), as the shield was of goatskin. Athene's aigis was a short goat-skin cloak, 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.)
certificate that a student is ill, Latin, literally "he is sick," third person singular of aegrotare "to be sick," from aeger "sick."
Aeneas
hero of the "Aeneid," son of Anchises and Aphrodite, Latin, from Greek Aineias, a name of unknown origin, perhaps literally "praise-worthy," from ainos "tale, story, saying, praise" (related to enigma); or perhaps related to ainos "horrible, terrible." The epic poem title Aeneid (late 15c. in English) is literally "of or pertaining to Aeneas," from French Enéide, Latin Æneida; see -id.
Aeolian (adj.)
also Aeolean, c. 1600, "of the wind," from Latin Æolus "god of the winds," from Greek Aiolos "lord of the winds," literally "the Rapid," or "the Changeable," from aiolos "quickly moving," also "changeful, shifting, varied" (an adjective used of wasps, serpents, flickering stars, clouds, sounds).

The Aeolian harp (the phrase is attested from 1791) was made of tuned strings set in a frame; passing breezes caused them to sound harmoniously. Another name for it was anemochord (1832). The ancient district of Aiolis in Asia Minor was said to have been named for the wind god, hence Aeolian also refers to one branch of the ancient Greek people.
Aeolus
Greek god of the winds, literally "the Rapid" or "the Changeable," from Greek aiolos (see Aeolian).
aeon (n.)
"immeasurable period of time," 1640s; see eon; also see æ (1).
aerate (v.)
"cause to mix with carbonic acid or other gas, 1794 (implied in aerated), from aer/aër (used in old science for specific kinds of air, a sense later given to gas (n.1)), from Latin aer (see air (n.1)) + verbal suffix -ate (2). Meaning "expose to air" is from 1799, probably a back-formation from aeration. Related: Aerating.
aeration (n.)
1570s, "act of exposing to air," from French aération, from aérer (v.), from Latin aer "the air, atmosphere" (see air (n.1)). In some cases, from aerate. In early scientific writing, aer/aër was used for specific kinds of air, a sense later given to gas (n.1).
aerator (n.)
1861, agent noun from aerate (v.).
aerial (adj.)
also aërial, c. 1600, "pertaining to the air," from Latin aerius "airy, aerial, lofty, high" (from Greek aerios "of the air, pertaining to air," from aer "air;" see air (n.1)). With adjectival suffix -al (1). Also in English "consisting of air," hence, figuratively, "of a light and graceful beauty; insubstantial" (c. 1600). From 1915 as "by means of aircraft." From the Latin collateral form aereus comes the alternative English spelling aereal.
aerial (n.)
1902, short for aerial antenna, etc.
aerie (n.)
"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 spelled eyrie (1660s) on the mistaken assumption that it derived from Middle English ey "egg."
aero-
word-forming element meaning "air, atmosphere; gases," in 20c. use with reference to aircraft or aviation, from Greek aer (genitive aeros) "air, lower atmosphere" (see air (n.1)).
aerobatics (n.)
"aircraft tricks, trick flying," 1914, from aero- + ending from acrobatics. Earlier (1879) it meant "the art of constructing and using airships; aerial navigation; aeronautics."
aerobic (adj.)
"able to live or living only in the presence of oxygen, requiring or using free oxygen from the air," 1875, after French aérobie (n.), coined 1863 by Louis Pasteur in reference to certain bacteria; from Greek aero- "air" (see aero-) + bios "life," from PIE root *gwei- "to live." Aerobian and aerobious also were used in English. Hence aerobe "type of micro-organism which lives on oxygen from the air." Meaning "pertaining to aerobics is from 1968.
aerobics (n.)
method of exercise and a fad in early 1980s, American English, coined 1968 by U.S. physician Kenneth H. Cooper (b. 1931), from aerobic (also see -ics) on the notion of activities which require modest oxygen intake and thus can be maintained.
aerodonetics (n.)
science of gliding, 1907, Modern Latin coinage by English engineer Frederick W. Lanchester (1868-1946) from Greek aer (genitive aeros) "air" (see air (n.1)) + stem of donein "to shake, drive about." Also see -ics.
aerodrome (n.)
1902, "hangar for airships," from aero- on analogy of hippodrome. From 1909 as "airport." Earlier (1891) a name for a flying machine, from Greek aerodromos "a running through the air."
aerodynamic (adj.)
also aero-dynamic, "pertaining to the forces of air in motion," 1847; see aero- + dynamic (adj.). Compare German aerodynamische (1835), French aérodynamique.
aerodynamics (n.)
"science of the motion of air or other gases," 1837, from aero- "air" + dynamics.
aerofoil (n.)
"lifting surface of an aircraft, etc.," 1907, from aero- + foil (n.).
aerogram (n.)
also aerogramme, 1899, "message sent through the air" (by radio waves, i.e. "wireless telegraphy"), from aero- + -gram. From 1920 as "air-mail letter."
aeronautics (n.)
1824, "art of aerial navigation by means of a balloon," from aeronautic (1784), from French aéronautique, from aéro- (see aero-) + nautique "of ships," from Latin nauticus, from Greek nautikos "pertaining to sailing" (see nautical). Originally of hot-air balloons. Also see -ics. Aeronaut "balloonist" is from 1784, from French aéronaute.
aerophobia (n.)
"morbid dread of a current of air," 1785; see aero- + phobia.
aerophyte (n.)
"plant which lives exclusively on air," 1838, perhaps via French aerophyte, from aero- "air" + -phyte "plant."
aeroplane (n.)
1866, originally in reference to surfaces such as shell casings of beetle wings, from French aéroplane (1855), from Greek-derived aero- "air" (see air (n.1)) + stem of French planer "to soar," from Latin planus "level, flat" (from PIE root *pele- (2) "flat; to spread").

The word was later extended to the wing of a heavier-than-air flying machine. The use of the word in reference to the machine itself is first attested 1873 and probably is an independent coinage in English. Also see airplane. Ancient Greek had a word aeroplanos, but it meant "wandering in the air," from planos "wandering" (see planet).
aerosol (n.)
1919, from aero- "air" + first syllable in solution, in the chemical sense. A term in physics; modern commercial application is from 1940s.
aerospace (adj.)
also aero-space, 1958, American English, from aero- "atmosphere" + (outer) space (n.).
Aeschylus
Greek Aiskhylos (525-456 B.C.E.), Athenian soldier, poet, and playwright, Father of Tragedy. The inscription on his tomb, said to have been written by him, mentions nothing of his fame as a poet but boasts that he had fought at Marathon. The name is said to be originally a nickname, "Little Ugly," a diminutive of aiskhos "ugly, ill-favored" (also "morally base, shameful"). Related: Aeschylean.
Aesculapius
Greek god of medicine, a Latinized form of Greek Aisklepios. Related: Aesculapian.
Aesir
collective name for the chief gods of the pagan 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 root *ansu- "spirit" (source also of first element in Ahura Mazda (q.v.)).
Aesop
Latinized form of Greek Aisopos, semi-legendary 6c. B.C.E. fablist. He was reputedly a slave, and very ugly; his stories were known to Herodotus and Aristophanes, but no direct writing of his survives.