Online Etymology Dictionary

also-ran (n.): 1896, originally in reference to horse-races, from also + past tense of run (v.). Probably from the way non-placing horses were listed in race results.
Altaic: 1832 as a linguistic family, from French Altaïque, from Altaïen, from Altai, name of a mountain range in Asia.
Altair: bright star in the constellation Aquila, 16c., from Arabic Al Nasr al Tair "the Flying Eagle," from tair, participle of tara "it flew."
altar (n.): Old English alter, altar, from Latin altare (plural altaria) "high altar, altar for sacrifice to the great gods," perhaps originally meaning "burnt offerings" (cf. Latin adolere "to worship, to offer sacrifice, to honor by burning sacrifices to"), but influenced by Latin altus "high." In Middle English, often auter, from Old French auter. Reintroduced from Latin 1500s. As a symbol of marriage, by 1820.
alter (v.): late 14c., "to change (something)," from Old French alterer "change, alter," from Medieval Latin alterare "to change," from Latin alter "the other (of the two)," from PIE *al- "beyond" (see alias (adv.)) + comparative suffix -ter (cf. other). Intransitive sense "to become otherwise" first recorded 1580s. Related: Altered; altering.
alter ego: 1530s, from Latin phrase (used by Cicero), "a second self, a trusted friend" (cf. Greek allos ego); see alter and ego.
alterable (adj.): 1520s, from alter + -able. Related: Alterably; alterability.
alteration (n.): late 14c., "action of altering," from Old French alteracion (14c.) "change, alteration," and directly from Medieval Latin alterationem (nominative alteratio), noun of action from past participle stem of Late Latin alterare (see alter). Meaning "change in character or appearance" is from 1530s; that of "change in ready-made clothes to suit a customer's specifications" is from 1901. Related: Alterations.
altercate (v.): 1520s, "to contend with words," from Latin altercatus, past participle of altercari (see altercation).
altercation (n.): late 14c., from Old French altercacion (12c.) and directly from Latin altercationem (nominative altercatio) "a dispute, debate, discussion," noun of action from past participle stem of altercari "to dispute (with another)," from alter "other" (see alter).
alternate (adj.): 1510s, from Latin alternatus "one after the other," past participle of alternare "to do first one thing then the other; exchange parts," from alternus "one after the other, alternate, in turns, reciprocal," from alter "the other" (see alter). Alternate means "by turns;" alternative means "offering a choice." Both imply two kinds or things.
alternate (v.): 1590s, from Latin alternatus, past participle of alternare (see alternate (adj.)). Replaced Middle English alternen "to vary, alternate" (early 15c.). Related: Alternated; alternating.
alternate (n.): 1718, "that which alternates (with anything else)," from alternate (adj.). Meaning "a substitute" is first attested 1848.
alternately (adv.): early 15c., from alternate (adj.) + -ly (2).
alternating (adj.): 1550s, present participle adjective from alternate (v.). Alternating current is recorded from 1839.
alternation (n.): mid-15c., from Old French alternacion, from Latin alternationem (nominative alternatio), noun of action from past participle stem of alternare (see alternate (v.)).
alternative (adj.): 1580s, "offering one or the other of two," from Medieval Latin alternativus, from Latin alternatus, past participle of alternare (see alternate (v.)). Meaning "purporting to be a superior choice to what is in general use" was current by 1970 (earliest reference is to the media); e.g. alternative energy (1975). Related: Alternatively.
alternative (n.): 1620s, in rhetoric, from Medieval Latin alternativus (see alternative (adj.)). Of courses of action, from 1814. Of objects, etc., "the other of two which may be chosen," by 1838.
alternator (n.): 1878, agent noun in Latin form from alternate (v.).
although (conj.): early 14c., althagh, compound of all + though, showing once-common emphatic use of all. "All though was originally more emphatic than though, but by 1400 it was practically only a variant of it, and all having thus lost its independent force, the phrase was written as one word" [OED].
altimeter (n.): 1918, from Modern Latin altimeter, from alti- "high" (from Latin altus; see old) + -meter.
altimetry (n.): 1690s, from Medieval Latin altimetria, from Latin alti- "high" (see old) + Greek -metria (see -metry).
altitude (n.): late 14c., from Latin altitudinem (nominative altitudo) "height, altitude," from altus "high" (see old).
alto (n.): 1784, "man with an alto voice," from Italian alto (canto), from Latin altus "high" (see old). Originally a "high" man's voice, now more commonly applied to the lower range of women's voices (which is more strictly the contralto), an extension first recorded in 1881.
The alto in a man is totally distinct from the contralto in a woman. The tone is utterly different -- the best notes of the one are certainly not the best notes of the other; and although in certain cases a contralto may sing with good effect music written for a male alto (e.g. in some oratorios), yet the converse is scarcely ever true. ["How to Sing," 1890]
As a type of saxophone, from 1869.
altogether: early 13c., altogedere, a strengthened form of all (also see together); used in the sense of "a whole" from 1660s. The altogether "nude" is from 1894.
altruism (n .): 1853, "unselfishness, opposite of egoism," from French altruisme, coined or popularized 1830 by French philosopher Auguste Comte (1798-1857), from autrui, from Old French altrui, "of or to others," from Latin alteri, dative of alter "other" (see alter). Apparently suggested to Comte by French legal phrase l'autrui, or in full, le bien, le droit d'autrui. The -l- is perhaps a reinsertion from the Latin word.
There is a fable that when the badger had been stung all over by bees, a bear consoled him by a rhapsodic account of how he himself had just breakfasted on their honey. The badger replied peevishly, "The stings are in my flesh, and the sweetness is on your muzzle." The bear, it is said, was surprised at the badger's want of altruism. ["George Eliot," "Theophrastus Such," 1879]
altruist (n.): 1842, from French; see altruism + -ist.
altruistic (adj.): 1853, from French altruiste (adj.), from altruisme (see altruism) + -ic.
alum (n.): late 14c., "whitish mineral salt used as an astringent, dye, etc.," from Old French alum, from Latin alumen "alum," literally "bitter salt," cognate with Greek aludoimos "bitter" and perhaps with English ale.
aluminium: see aluminum.
aluminum (n.): 1812, coined by English chemist Sir Humphry Davy (1778-1829), from alumina, name given 18c. to aluminum oxide, from Latin alumen "alum" (see alum). Davy originally called it alumium (1808), then amended this to aluminum, which remains the U.S. word, but British editors in 1812 further amended it to aluminium, the modern preferred British form, to better harmonize with other metallic element names (sodium, potassium, etc.).
Aluminium, for so we shall take the liberty of writing the word, in preference to aluminum, which has a less classical sound. ["Quarterly Review," 1812]
alumna (n.): see alumnus.
alumnae (n.): see alumnus.
alumni (n.): see alumnus.
alumnus (n.): 1640s, from Latin alumnus "a pupil," literally "foster son," vestigial present passive participle of alere "to nourish" (see old), with ending akin to Greek -omenos. Plural is alumni. Fem. is alumna (1882), fem. plural alumnae.
alveolar (adj.): "pertaining to alveoli," 1799, from Modern Latin alveolus "socket of a tooth" (see alveolus).
alveolus (n.): 1706, from Latin alveolus "a tray, trough, basin; bed of a small river," diminutive of alvus "belly, stomach, paunch, bowels; hold of a ship," from PIE *aulo- "hole, cavity" (cf. Greek aulos "tube, pipe," Old Church Slavonic uliji, Lithuanian aulys "beehive" (hollow trunk), Armenian yli "pregnant").
always (adv.): mid-14c., compound of Old English phrase ealne weg "always, quite, perpetually," literally "all the way," with accusative of space or distance, though the oldest recorded usages refer to time. The adverbial genitive -s appeared early 13c. and is now the standard, though the variant alway survived into 1800s. OED speculates allway was originally of space or distance, "but already in the oldest Eng. transferred to an extent of time."
Alyssum (n.): genus name for plants of the mustard family, 1550s, from Latin alysson, from Greek alysson, which is perhaps the neuter of adjective alyssos "curing madness," from privative prefix a- + lyssa "madness, rage, fury."
Alzheimer's disease: (senium præcox), 1912, title of article by S.C. Fuller published in "Journal of Nervous and Mental Diseases;" named for German neurologist Alois Alzheimer (1864-1915). The name was not common before 1970s; shortened form Alzheimer's first recorded 1954. The surname is from the place name Alzheim, literally "Old Hamlet."
am (v.): Old English eom "to be, to remain," (Mercian eam, Northumbrian am), from PIE *esmi- (cf. Old Norse emi, Gothic im, Hittite esmi, Old Church Slavonic jesmi, Lithuanian esmi), from root *es-, the S-ROOT, which also yielded Greek esti-, Latin est, Sanskrit as-, and German ist.

In Old English it existed only in present tense, all other forms being expressed in the W-BASE (see were, was). This cooperative verb is sometimes referred to by linguists as *es-*wes-. Until the distinction broke down 13c., *es-*wes- tended to express "existence," with beon meaning something closer to "come to be" (see be).

Old English am had two plural forms: 1. sind/sindon, sie and 2. earon/aron The s- form (also used in the subjunctive) fell from use in English in the early 13c. (though it continues in German sind, the 3rd person plural of "to be") and was replaced by forms of be, but aron (aren, arn, are, from Proto-Germanic *ar-, probably a variant of PIE root *es-) continued, and as am and be merged it encroached on some uses that previously had belonged to be. By the early 1500s it had established its place in standard English. Art became archaic in the 1800s.
amable (adj.): "friendly, courteous," early 15c., from Old French amable, from Latin amabilem "lovely," from amare "to love" (see Amy). Related: Amably; amability.
amah (n.): "wet-nurse," 1839, Anglo-Indian, from Portuguese ama "nurse," from Medieval Latin amma "mother," from PIE root *am-, forming nursery words.
amain (adv.): 1530s, from main (adj.) by analogy with other words in a- (e.g. afoot).
amalgam (n.): c.1400, "blend of mercury with another metal; soft mass formed by chemical manipulation," from Old French amalgame or directly from Medieval Latin amalgama, "alloy of mercury (especially with gold or silver)," an alchemists' word, perhaps an alteration of Latin malagma "poultice, plaster," probably from Arabic al-malgham "an emollient poultice or unguent for sores (especially warm)" [Francis Johnson, "A Dictionary of Persian, Arabic, and English"], perhaps from Greek malagma "softening substance," from malassein "to soften," from malakos "soft."
amalgamate (v.): 1650s, back-formation from amalgamation, or from adjective amalgamate (1640s) from amalgam. Originally in metallurgy; figurative sense of "to unite" (races, etc.) is attested from 1802. Related: Amalgamated; amalgamating. Earlier verb was amalgamen (1540s).
amalgamation (n.): 1610s, noun of action from archaic amalgam (v.) "to alloy with mercury" (see amalgamate). Figurative, non-chemical sense of "a combining into one uniform whole" is attested from 1775.
amalgamize (v.): 1590s, from amalgam + -ize. Related: Amalgamized; amalgamizing.
Amanda: fem. proper name, literally "worthy to be loved," fem. of Latin amandus "pleasing," gerundive of amare "to love" (see Amy). A top 10 list name for girls born in U.S. between 1976 and 1995.
amanuensis (n.): "one who takes dictation," 1610s, from Latin amanuensis "adjective used as a noun," from servus a manu "secretary," literally "servant from the hand," from a "from" + manu, ablative of manus "hand" (see manual (adj.)).