Online Etymology Dictionary

atrophy (v.): 1822 (implied in atrophied), from atrophy (n.). Related: Atrophying.
atropine (n.): 1836, from Latin atropa "deadly nightshade" (from which the alkaloid poison is extracted), from Greek atropos "inflexible," also the name of one of the Fates (see Atropos) + chemical suffix -ine (2).
Atropos: one of the Fates (the one who holds the shears and determines the manner of a person's death and cuts the thread), from Greek, "inflexible," literally "not to be turned away," from a- "not" (see a- (3)) + stem of trepein "to turn" (see trope). Related form Atropa was the Greek name for deadly nightshade.
attaboy: 1909, probably from common pronunciation of "that's the boy!" a cheer of encouragement or approval.
attach (v.): mid-14c. (mid-13c. in Anglo-Latin), "to take or seize (property or goods) by law," a legal term, from Old French atachier (11c.), earlier estachier "to attach, fix; stake up, support" (Modern French attacher, also compare Italian attaccare), perhaps from a- "to" + Frankish *stakon "a post, stake" or a similar Germanic word (see stake (n.)). Meaning "to fasten, affix, connect" is from c. 1400. Related: Attached; attaching.
attachable (adj.): 1570s, from attach + -able.
attache (n.): 1835, from French attaché "junior officer attached to the staff of an ambassador, etc.," literally "attached," past participle of attacher "to attach" (see attach). Attache case "small leather case for carrying papers" first recorded 1900.
attached (adj.): "affectionate, devoted, fond," 1793, past participle adjective from attach.
attachment (n.): c. 1400, "arrest of a person on judicial warrant" (mid-13c. in Anglo-Latin), from French attachement, from attacher (see attach). Application to property (including, later, wages) dates from 1590s; meaning "sympathy, devotion" is recorded from 1704; that of "something that is attached to something else" dates from 1797 and has become perhaps the most common use since the rise of e-mail.
attack (v.): c. 1600, from French attaquer (16c.), from Florentine Italian attaccare (battaglia) "join (battle)," thus the word is a doublet of attach, which was used 15c.-17c. also in the sense now reserved to attack. Related: Attacked; attacking.
attack (n.): 1660s, from attack (v.). Compare Middle English attach "a seizure or attack" (of fever), late 14c.
attain (v.): c. 1300, "to succeed in reaching," from ataign-, stem of Old French ataindre (11c., Modern French atteindre) "to come up to, reach, attain, endeavor, strive," from Vulgar Latin *attangere, corresponding to Latin attingere "to touch, to arrive at," from ad- "to" (see ad-) + tangere "to touch" (see tangent (adj.)). Latin attingere had a wide range of meanings, including "to attack, to strike, to appropriate, to manage," all somehow suggested by the literal sense "to touch." Related: Attained; attaining.
attainable (adj.): 1640s; see attain + -able. Related: Attainability.
attainder (n.): "extinction of rights of a person sentenced to death or outlaw," mid-15c., from noun use of Old French ataindre "to touch upon, strike, hit, seize, accuse, condemn" (see attain). For use of French infinitives as nouns, especially in legal language, see waiver.
attainment (n.): late 14c., "encroachment" (a sense now obsolete), from Old French ataignement (Modern French atteignement), from ataindre; see attain. Meaning "action of attaining" is from 1540s; sense of "that which is attained, personal accomplishment" dates from 1670s.
attar (n.): 1798, from Persian 'atar-gul "essence of roses," from 'atar "fragrance," from Arabic 'utur "perfumes, aromas."
attemper (v.): late 14c., from Old French attemprer, from Latin attemperare, from ad- "to" (see ad-) + temperare "to mix in due proportion, modify, blend; restrain oneself" (see temper (v.)). Related: Attempered; attempering.
attempt (v.): late 14c., from Old French attempter (14c.), earlier atenter "to try, attempt, test," from Latin attemptare "to try" (source also of Italian attentare, Old Provençal, Portuguese attentar, Spanish atentar), from ad- "to, upon" (see ad-) + temptare "to try" (see tempt). Related: Attempted; attempting.
attempt (n.): 1530s, from attempt (v.). Meaning "effort to accomplish something by violence" is from 1580s, especially as an assault on someone's life.
attend (v.): c. 1300, "to direct one's mind or energies," from Old French atendre (12c., Modern French attendre) "to expect, wait for, pay attention," and directly from Latin attendere "give heed to," literally "to stretch toward," from ad- "to" (see ad-) + tendere "stretch" (see tenet). The notion is of "stretching" one's mind toward something. Sense of "take care of, wait upon" is from early 14c. Meaning "to pay attention" is early 15c.; that of "to be in attendance" is mid-15c. Related: Attended; attending.
attendance (n.): late 14c., "act of attending to one's duties," from Old French atendance "attention, wait, hope, expectation," from atendant, present participle of atendre (see attend). Meaning "action of waiting on someone" dates from late 14c. (to dance attendance on someone is from 1560s); that of "action of being present, presenting oneself" (originally with intent of taking a part) is from mid-15c. Meaning "number of persons present" is from 1835.
attendant (n.): 1550s, "one who waits upon," from the adjective, or from Middle French atendant, noun use of present participle of atendre (see attend).
attendant (adj.): late 14c., "solicitous, attentive," see attendant (n.). Sense of "serving under, accompanying in a dependant position" is from c. 1400.
attendee (n.): "one who attends" (something), 1961, from attend + -ee. Attender is older (mid-15c.) but had senses "one who waits upon" and "one who gives heed."
attent (adj.): late 15c., "attentive," from Latin attentus, past participle of attendere (see attend). As a noun, "intention, aim" (early 13c.), from Old French atente "act of attending," from fem. of Latin attentus.
attention (n.): late 14c., "giving heed," from Latin attentionem (nominative attentio) "attention, attentiveness," noun of action from past participle stem of attendere "mental heeding" (see attend). Used with a remarkable diversity of verbs (such as pay, gather, attract, draw, call). As a military cautionary word preparative to giving a command, it is attested from 1792. Attention span is from 1903 (earlier span of attention, 1892).
attention deficit disorder (n.): (abbreviated ADD) became a diagnosis in the third edition of the "Diagnostic and Statistical Manual of Mental Disorders" (1980); expanded to attention deficit hyperactivity disorder ("the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone;" ADHD) in DSM-III (1987).
attentive (adj.): late 14c. (implied in attentively), from Old French attentif, from Vulgar Latin *attenditus, from Latin attentus "heedful, observant" (see attend). Sense of "actively ministering to the needs and wants" (of another person) is from early 16c. Related: Attentively.
attentiveness (n.): mid-15c., from attentive + -ness.
attenuate (v.): "to make thin, to make less," 1520s, from Latin attenuatus "enfeebled, weak," past participle of attenuare "to make thin, lessen, diminish," from ad- "to" (see ad-) + tenuare "make thin," from tenuis "thin" (see tenet). Related: Attenuated; attenuating. Earlier was Middle English attenuen "to make thin (in consistency)," early 15c.
attenuation (n.): early 15c., of persons, "emaciation;" of diet, "reduction," from Latin attenuationem (nominative attenuatio) "a lessening," noun of action from past participle stem of attenuare (see attenuate).
attercop (n.): "spider," Old English attorcoppe, literally "poison-head," from ator "poison, venom," from Proto-Germanic *aitra- "poisonous ulcer" (source also of Old Norse eitr, Old High German eitar "poison;" German eiter "pus," Old High German eiz "abscess, boil;" Old English atorcræft "art of poisoning") + copp "top, summit, round head," probably also "spider" (compare cobweb and Dutch spinne-cop "spider").
Amptes & attircoppes & suche oþer þat ben euere bisy ben maide to schewe man ensaumple of stodye & labour. [Elucidarium of Honorius of Autun (Wycliffite version) c. 1400]
attest (v.): 1590s, from Middle French attester (Old French atester, 13c.) "affirm, attest," from Latin attestari "confirm," literally "bear witness to," from ad- "to" (see ad-) + testari "bear witness," from testis "witness" (see testament). Related: Attested; attesting.
attestation (n.): mid-15c., from Middle French attestation and directly from Latin attestationem (nominative attestatio) "an attesting, testimony," noun of action from past participle stem of attestari "to prove, confirm" (see attest).
Attic (adj.): 1590s, "pertaining to Attica," from Latin Atticus, from Greek Attikos "Athenian, of Attica," the region around Athens (see Attica). Attested from 1560s as an architectural term for a type of column base.
attic (n.): "top story under the roof of a house," 1855, shortened from attic storey (1724). The term Attic order in classical architecture meant a small, square decorative column of the type often used in a low story above a building's main facade, a feature associated with the region around Athens (see Attic). The word then was applied by architects to "a low decorative facade above the main story of a building" (1690s in English) to convey a classical heritage where none exists, and it came to mean the space enclosed by such a structure. The modern use is via French attique. "An attic is upright, a garret is in a sloping roof" [Weekley].
Attica: traditionally explained as from Greek Attikos (Latin Atticus) "of Athens" (see Athens); but perhaps ultimately from Greek akte "shore, maritime place," also "raised place."
attire (v.): c. 1300, "to fit out, equip; to dress in finery, to adorn," from Old French atirier "to equip, ready, prepare," from a- "to" + tire "order, row, dress" (see tier). Related: Attired; attiring.
attire (n.): c. 1300, "equipment of a man-at-arms; fine apparel," from attire (v.).
attitude (n.): 1660s, via French attitude (17c.), from Italian attitudine "disposition, posture," also "aptness, promptitude," from Late Latin aptitudinem (nominative aptitudo; see aptitude). Originally 17c. a technical term in art for the posture of a figure in a statue or painting; later generalized to "a posture of the body supposed to imply some mental state" (1725). Sense of "settled behavior reflecting feeling or opinion" is first recorded 1837. Connotations of "antagonistic and uncooperative" developed by 1962 in slang.
attitudinal (adj.): 1831, from Italian attitudine (see attitude) + -al (1).
attitudinize (v.): 1784, from attitudinal + -ize. Related: Attitudinized; attitudinizing.
atto-: word-forming element meaning "one quintillionth," 1962, from Danish atten "eighteen" (a quintillion is 10 to the 18th power), related to Old English eahtatene (see eighteen).
attorn (v.): late 13c., Anglo-French, "to turn over to another," from Old French atorner "to turn, turn to, assign, attribute, dispose," from a- "to" (see ad-) + tourner "to turn" (see turn (v.)). In feudal law, "to transfer homage or allegiance to another lord."
attorney (n.): early 14c. (mid-13c. in Anglo-Latin), from Old French atorné "(one) appointed," past participle of aturner "to decree, assign, appoint," from atorner (see attorn). The legal Latin form attornare influenced the spelling in Anglo-French. The sense is of "one appointed to represent another's interests."

In English law, a private attorney was one appointed to act for another in business or legal affairs (usually for pay); an attorney at law or public attorney was a qualified legal agent in the courts of Common Law who prepared the cases for a barrister, who pleaded them (the equivalent of a solicitor in Chancery). So much a term of contempt in England that it was abolished by the Judicature Act of 1873 and merged with solicitor.
Johnson observed that "he did not care to speak ill of any man behind his back, but he believed the gentleman was an attorney." [Boswell]
The double -t- is a mistaken 15c. attempt to restore a non-existent Latin original. Attorney general first recorded 1530s in sense of "legal officer of the state" (late 13c. in Anglo-French), from French, hence the odd plural (subject first, adjective second).
attract (v.): early 15c., from Latin attractus, past participle of attrahere "to draw, pull; to attract," from ad- "to" (see ad-) + trahere "draw" (see tract (n.1)).

Originally a medical term for the body's tendency to absorb fluids, nourishment, etc., or for a poultice treatment to "draw out" diseased matter (1560s). Of the ability of people or animals to draw others to them, it is attested from 1560s; of physical forces (magnetism, etc.), from c. 1600 (implied in attraction). Related: Attracted; attracting.
attraction (n.): late 14c., from French attraction, from Latin attractionem (nominative attractio) "a drawing together," noun of action from past participle stem of attrahere (see attract). Originally a medical word, "absorption by the body;" meaning "action of drawing to" is from 1540s (again medical); extended to magnetic, then figuratively to personal (c. 1600) qualities. Meaning "a thing which draws a crowd, interesting or amusing exhibition" is from 1829, a sense that developed in English and soon transferred to the French equivalent of the word.
attractive (adj.): late 14c., "absorptive," from Middle French attractif (14c.), from attract-, past participle stem of attrahere (see attract). Meaning "having the quality of drawing people's eye or interest" is from 1580s; sense of "pleasing, alluring" is from c. 1600. Related: Attractively; attractiveness.
attrahent (n.): "that which attracts," 1660s, from Latin attrahentem (nominative attrahens), present participle of attrahere (see attract).
attributable (adj.): 1660s, from attribute (v.) + -able.