aggrieved (adj.)
c. 1300, "annoyed, incensed, resentful, angry;" late 14c., "oppressed in spirit," past participle adjective from aggrieve (v.). The legal sense of "injured or wronged in one's rights" is from 1580s.
aggro (n.)
by 1969, originally British underworld and juvenile delinquent slang, short for aggravation in a colloquial sense "trouble or disturbance provoked by aggressive behavior or harassment" (by 1939).
aghast (adj.)
c. 1300, agast, "terrified, suddenly filled with frightened amazement," past participle of Middle English agasten "to frighten" (c. 1200), from a- intensive prefix (see a- (1)) + Old English gæstan "to terrify," from gæst "spirit, ghost" (see ghost (n.)). The unetymological -gh- is perhaps a Flemish influence, or after ghost, etc. It became general after 1700.
agile (adj.)
"having quickness of motion, nimble, active" (of body or mind), 1580s, from Middle French agile (14c.) and directly from Latin agilis "nimble, quick," from agere "to set in motion, keep in movement" (from PIE root *ag- "to drive, draw out or forth, move"). Related: Agilely.
agility (n.)
early 15c., "nimbleness, quickness," from Old French agilité (14c.), from Latin agilitatem (nominative agilitas) "mobility, nimbleness, quickness," from agilis "nimble, quick," from agere "to set in motion; keep in movement" (from PIE root *ag- "to drive, draw out or forth, move"). Of mental swiftness from mid-15c.
agin (prep.)
in modern use a representation of dialectal pronunciation of again or against.
aging (n.)
also ageing, "process of imparting age or the qualities of age to," 1860, verbal noun from age (v.).
agism (n.)
alternative spelling of ageism (q.v.).
agitate (v.)
1580s, "to disturb," from Latin agitatus, past participle of agitare "to put in constant or violent motion, drive onward, impel," frequentative of agere "to set in motion, drive, drive forward," figuratively "incite to action; keep in movement, stir up" (from PIE root *ag- "to drive, draw out or forth, move").

Literal sense of "move to and fro, shake" is from 1590s. Meaning "to discuss, debate" is from 1640s, that of "keep (a political or social question) constantly im public view" is by 1828. Related: Agitated; agitating.
agitated (adj.)
1610s, "set in motion," past participle adjective from agitate (v.). Meaning "disturbed" is from 1650s; that of "disturbed in mind" is from 1756. Meaning "kept constantly in public view" is from 1640s.
agitation (n.)
1560s, "debate, discussion" (on the notion of "a mental tossing to and fro"), from French agitation, from Latin agitationem (nominative agitatio) "motion, agitation," noun of action from past participle stem of agitare "move to and fro," frequentative of agere "to set in motion, drive forward; keep in movement" (from PIE root *ag- "to drive, draw out or forth, move"). Physical sense of "state of being shaken or moving violently" is from 1580s; meaning "state of being mentally agitated" is from 1722; that of "arousing and sustaining public attention" to some political or social cause is from 1828.
agitator (n.)
1640s, agent noun from agitate (v.); originally "elected representative of the common soldiers in Cromwell's army," who brought grievances (chiefly over lack of pay) to their officers and Parliament.

Political sense is first recorded 1734, and negative overtones began with its association with Irish patriots such as Daniel O'Connell (1775-1847). Historically, in American English, often with outside and referring to people who stir up a supposedly contented class or race. Latin agitator meant "a driver, a charioteer."
agitprop (n.)
also agit-prop, 1938, from Russian agitatsiya "agitation" (from French agitation; see agitation) + propaganda (see propaganda), which Russian got from German.
name of one of the Graces, Greek, literally "splendor, beauty, brightness," from aglaos "splendid, beautiful, bright," which is of unknown origin (probably connected with agauos "noble, illustrious;" see agave), + abstract noun ending -ia.
agleam (adj.)
"gleaming," 1854, from a- (1) + gleam (v.).
aglet (n.)
also aiglet, "metal tag of a lace," meant to make it easier to thread through the eyelet-holes, but later merely ornamental, mid-15c., from Middle French aiguillette, diminutive of aiguille "needle," from Late Latin acucula, an extended form (via diminutive suffix, but not necessarily implying smallness) of Latin acus "a needle," from PIE root *ak- "be sharp, rise (out) to a point, pierce." Compare Italian agucchia, Portuguese agulha, Spanish aguja "needle."
aglimmer (adj.)
1828, from a- (1) + glimmer (v.).
aglow (adj.)
1817 (in Coleridge), from a- (1) + glow (v.). Figurative sense of "flushed with pleasurable excitement" is from 1830.
agnail (n.)
see hangnail.
fem. proper name, mid-12c., from Old French Agnes, from Greek Hagne "pure, chaste," fem. of hagnos "holy, sacred" (of places); "chaste, pure; guiltless, morally upright" (of persons), from PIE *yag-no-, suffixed form of root *yag- "to worship, reverence" (see hagiology).

St. Agnes, martyred 303 C.E., is patron saint of young girls, hence the folk connection of St. Agnes' Eve (Jan. 20-21) with love divinations. In Middle English, frequently written phonetically as Annis, Annys. In U.S., among the top 50 names for girls born between 1887 and 1919.
agnostic (n.)
1870, "one who professes that the existence of a First Cause and the essential nature of things are not and cannot be known" [Klein]; coined by T.H. Huxley (1825-1895), supposedly in September 1869, from Greek agnostos "unknown, unknowable," from a- "not" (see a- (3)) + gnostos "(to be) known," from PIE root *gno- "to know." Sometimes said to be a reference to Paul's mention of the altar to "the Unknown God" in Acts, but according to Huxley it was coined with reference to the early Church movement known as Gnosticism (see Gnostic).
I ... invented what I conceived to be the appropriate title of 'agnostic,' ... antithetic to the 'Gnostic' of Church history who professed to know so much about the very things of which I was ignorant. [T.H. Huxley, "Science and Christian Tradition," 1889]

The agnostic does not simply say, "I do not know." He goes another step, and he says, with great emphasis, that you do not know. [Robert G. Ingersoll, "Reply to Dr. Lyman Abbott," 1890]
The adjective also is first recorded 1870.
agnosticism (n.)
1870, from agnostic + -ism.
Agnus Dei (n.)
Late Latin, literally "lamb of God." From c. 1400 in English as the name of the part of the Mass beginning with these words, or (later) a musical setting of it. Latin agnus "lamb" is from PIE *agwh-no- "lamb" (see yean). For deus "god," see Zeus. The phrase is used from 1620s in reference to an image of a lamb as emblematic of Christ; usually it is pictured with a nimbus and supporting the banner of the Cross.
ago (adj.)
"gone, gone by; gone away," early 14c., a shortened form of agon "departed, passed away," past participle of a now-obsolete verb ago, agon "to go, proceed, go forth, pass away, come to an end," from Old English agan. This was formed from a- (1) "away" (perhaps here used as an intensive prefix) + gan "to go" (see go (v.)).

As an adverb, "in past times" (as in long ago) from late 14c. The form agone is now obsolete except as a dialectal variant.
agog (adv.)
"in a state of desire; in a state of imagination; heated with the notion of some enjoyment; longing" [Johnson], c. 1400, perhaps from Old French en gogues "in jest, good humor, joyfulness," from gogue "fun," which is of unknown origin.
agon (n.)
1650s, in reference to ancient Greece, "contest for a prize," from Greek agon "struggle, trial," especially in the public games (see agony) but also of contests for prizes in poetry, theater, music. Meaning "verbal dispute between characters in a Greek play" is from 1887. Related: Agonal.
All over Greece we find all endeavor taking the form of a contest, an agon. Before the age of Archilochos, Sappho, and Alkman, we hear of contests of trumpets, city against city, the splendor of which tantalizes the imagination more than all the kings and archons in the history books. [Guy Davenport, "7 Greeks"]
agonic (adj.)
"having no angle," 1846, from Greek agonos, from a- "not" (see a- (3)) + -gonos "angled," from gonia "angle" (from PIE root *genu- (1) "knee; angle"). In reference to the imaginary line on the earth's surface connecting points where the magnetic declination is zero.
agonist (n.)
1876, in writings on Greek drama, "a hero (attacked in the play by an antagonist)," from Latin agonista, Greek agonistes "rival combatant in the games, competitor; opponent (in a debate)," also, generally "one who struggles (for something)," from agonia "a struggle for victory" (in wrestling, etc.), in a general sense "exercise, gymnastics;" also of mental struggles, "agony, anguish" (see agony). Agonistes as an (ironic) epithet seems to have been introduced in English by T.S. Eliot (1932).
agonistic (adj.)
"pertaining to an agonist," 1640s, from Latinized form of Greek agonistikos, from agonistes (see agonist).
agonize (v.)
1580s, "to torture" (trans.), from Middle French agoniser (14c.) or directly from Medieval Latin agonizare "to labor, strive, contend," also "be at the point of death," from Greek agonizesthai "contend in the struggle, contend for victory or a prize" (in reference to physical combat, stage competitions, lawsuits), from agonia "a struggle for victory," originally "a struggle for victory in the games" (see agony). Intransitive sense of "suffer extreme physical pain" is recorded from 1660s; mental sense of "to worry intensely" is from 1853. Related: Agonized; agonizing.
agony (n.)
late 14c., "mental suffering" (especially that of Christ in the Garden of Gethsemane), from Old French agonie, agoine "anguish, terror, death agony" (14c.), and directly from Late Latin agonia, from Greek agonia "a struggle for victory" (in wrestling, etc.), in a general sense "exercise, gymnastics;" also of mental struggles, "agony, anguish." This is from agon "assembly, mass of people brought together," especially to watch the games, hence, "a contest," then, generally, "any struggle or trial;" from the verb agein "put in motion, move" (here specifically as "assemble, bring together"), from PIE root *ag- "to drive, draw out or forth, move."

Specifically of the struggle that precedes natural death (mortal agony) from 1540s. The sense development perhaps involves "pain so severe as to cause struggling." Sense of "extreme bodily suffering" first recorded c. 1600.
agora (n.)
1590s, "open assembly place, chief public square and marketplace of a town; popular political assembly held in such a place," from Greek agora "an assembly of the People" (as opposed to a council of Chiefs); "the place of assembly; a marketplace" (the typical spot for such an assembly), from ageirein "to assemble," from PIE root *ger- (1) "gather, gather together, assemble" (see gregarious). The Greek word also could mean "public speaking," and "things to be sold." For sense, compare Roman forum.
agoraphobia (n.)
"fear of crossing open spaces," 1873, from German Agorophobie, coined 1871 by Berlin psychiatrist Carl Westphal (1833-1890) from Greek agora "place of assembly, city market" (but here with the general sense "open space;" see agora) + -phobia "fear." Related: Agoraphobe; agoraphobic.
agrarian (adj.)
1610s, "relating to the land," from Middle French agrarienne, from Latin agrarius "of the land," from ager (genitive agri) "a field," from PIE root *agro- "field." Specialized meaning "having to do with cultivated land" first recorded 1792. Originally, and often subsequently, "pertaining to the division or sharing of landed property," which was the Roman sense. Earlier in English as agrarie (1530s), from Latin agraria.
agree (v.)
late 14c., "to give consent, assent," from Old French agreer "to please, satisfy; to receive with favor, take pleasure in" (12c.), a contraction of phrase a gré "favorably, of good will," literally "to (one's) liking" (or a like contraction in Medieval Latin) from a, from Latin ad "to" (see ad-) + Old French gre, gret "that which pleases," from Latin gratum, neuter of gratus "pleasing, welcome, agreeable" (from suffixed form of PIE root *gwere- (2) "to favor").

In Middle English also "to please, gratify, satisfy," a sense preserved in agreeable. Of parties, "come to agreement; make a settlement," mid-15c.; meaning "to be in harmony in opinions" is from late 15c. Of things, "to coincide," from 1520s. To agree to differ is from 1785 (also agree to disagree, 1792). Related: Agreed; agreeing.
agreeable (adj.)
late 14c., of things, "to one's liking, pleasant, satisfactory, suitable," from Old French agreable "pleasing; in agreement; consenting" (12c., Modern French agréable), from agreer "to satisfy; to take pleasure in" (see agree). Of persons, "willing or ready to consent," mid-15c. Related: Agreeably; agreeability; agreeableness. To do the agreeable (1825) was to "act in a courteous manner."
agreeance (n.)
1530s, from Middle French agréance, noun of action from agréer "to please, satisfy; take pleasure in" (see agree).
agreement (n.)
c. 1400, "mutual understanding" (among persons), also (of things) "mutual conformity," from Old French agrement, agreement, noun of action from agreer "to please" (see agree). Early 15c. as "formal or documentary agreement, terms of settlement."
agribusiness (n.)
also agri-business, 1955, compound formed from agriculture + business.
agricultural (adj.)
1766, from agriculture + -al (1). Related: Agriculturally; agriculturalist.
agriculture (n.)
mid-15c., "tillage, cultivation of large areas of land to provide food," from Late Latin agricultura "cultivation of the land," a contraction of agri cultura "cultivation of land," from agri, genitive of ager "a field" (from PIE root *agro- "field") + cultura "cultivation" (see culture (n.)). In Old English, the idea could be expressed by eorðtilþ.
agriology (n.)
study of prehistoric human customs, 1878, from agrio-, from Greek agrios "wild," literally "living in the fields," from agros "field" (from PIE root *agro- "field") + -logy. Related: Agriologist (n., 1875); agriological.
word-forming element meaning "pertaining to agriculture or cultivation," from Greek agro-, comb. form of agros "field," from PIE root *agro- "field."
agronomy (n.)
"science of land management for crop production," 1796, from French agronomie (1761), from Greek agronomos "overseer of land," from agros "a field, a farm; the country," as opposed to the town (from PIE root *agro- "field") + nomos "law or custom, administering," related to nemein "manage" (from PIE root *nem- "assign, allot"). Related: Agronomist; agronomic.
aground (adv.)
late 13c., "on the ground," from a- "on" (see a- (1)) + ground (n.). Of ships and boats, "stranded," from c. 1500.
ague (n.)
c. 1300, "acute fever," also (late 14c.) "malarial fever (involving episodes of chills and shivering)" from Old French ague "acute fever," from Medieval Latin (febris) acuta "sharp (fever)," from fem. of acutus "sharp" (from PIE root *ak- "be sharp, rise (out) to a point, pierce").
ah (interj.)
mid-15c., an expression of surprise, delight, disgust, or pain in nearly all Indo-European languages, but not found in Old English (where the equivalent expression was la!), so perhaps from Old French a "ah!, oh! woe!"
aha (interj.)
expression of surprise or delighted discovery, late 14c., from ah + ha.
This seely widewe and hire doughtres two ... cryden out "harrow!" and "weloway! A ha! þe fox!" and after him they ran [Chaucer]
ahead (adv.)
1620s, "at the head, in front," from a- "on" (see a- (1)) + head (n.) "front." Originally nautical (opposed to astern). Meaning "forward, onward" (the sense in go ahead) is from 1640s. To be ahead of (one's) time attested by 1837.
attention-getting interjection, 1763, lengthened from hem, imitative of clearing the throat.