Online Etymology Dictionary

account (n.): c.1300, "reckoning of money received and paid," from Old French acont "account, reckoning, terminal payment," from a "to" (see ad-) + cont "counting, reckoning of money to be paid," from Late Latin computus "a calculation," from Latin computare "calculate" (see compute).

Meaning "sum of (one's) money in a bank" is from 1833. Sense of "narration" is first attested 1610s. Plural accounts used as a collective or singular in phrases such as to give accounts (of something), is from mid-13c. Phrase by all accounts is attested from 1798.
account (v.): c.1300, "to count, enumerate," from Old French aconter "to count, render account" (Modern French conter), from a "to" (see ad-) + conter "to count, tell" (see count (v.)). Meaning "to reckon for money given or received, render a reckoning," is from late 14c.; sense of "to explain" (c.1710) is from notion of "answer for money held in trust." Transferred sense of "value" is from late 14c. Related: Accounted; accounting.
accountability (n.): 1770, from accountable + -ity. Earlier was accountableness (1660s).
accountable (adj.): "answerable," literally "liable to be called to account," c.1400 (mid-14c. in Anglo-French); see account (v.) + -able. Related: Accountably.
accountancy (n.): 1854, from accountant + -cy.
accountant (n.): mid-15c., "accounting officer, one who renders accounts," from Old French acuntant (Modern French accomptant), from present participle of accompter (see account). Sense of "professional maker of accounts" is recorded from 1530s. The word also was an adjective in Middle English, "accountable; liable to render accounts" (early 15c.).
accounting (n.): "reckoning of numbers," late 14c., verbal noun from account (v.). Phrase no accounting for tastes (1823) translates Latin de gustibus non est disputandum.
accouter (v.): also accoutre, 1590s, from French acoutrer, earlier acostrer (13c.) "arrange, dispose, put on (clothing)," originally "sew up," from Vulgar Latin accosturare "to sew together, sew up," from Latin ad- "to" (see ad-) + *consutura "a sewing together," from Latin consutus, past participle of consuere "to sew together," from con- (see com-) + suere "to sew" (see suture). Related: Accoutered; accoutred; accoutering; accoutring.
accoutrements (n.): 1540s, from Middle French accoustrement (Modern French accoutrement), from accoustrer probably from Old French acostrer "arrange," originally "sew up" (see accouter)
accredit (v.): 1610s, from French accréditer, from à "to" (see ad-) + créditer "to credit" (someone with a sum), from crédit "credit" (see credit). Related: Accredited; accrediting.
accreditation (n.): 1806, noun of action from accredit.
accredited (adj.): "furnished with credentials," 1630s, past participle adjective from accredit (v.).
accretion (n.): 1610s, from Latin accretionem (nominative accretio) "an increasing, a growing larger" (e.g. of the waxing moon), noun of action from past participle stem of accrescere, from ad- "to" (see ad-) + crescere "grow" (see crescent).
accrual (n.): 1782, from accrue + -al (2).
accrue (v.): mid-15c., from Old French acreue "growth, increase, what has grown," fem. of acreu, past participle of acreistre (Modern French accroître) "to increase," from Latin accrescere (see accretion). Related: Accrued; accruing.
acculturate (v.): 1934, back-formation from acculturation. Related: Acculturated; acculturating.
acculturation (n.): "the adoption and assimilation of an alien culture," 1880, from ad- "to" + culture (n.) + -ation.
accumulate (v.): 1520s, from Latin accumulatus, past participle of accumulare "to heap up" (see accumulation). Related: Accumulated; accumulating.
accumulated (adj.): past participle adjective from accumulate (v.). It drove out accumulate (adj.) in this sense (except in poetic use) by c.1700.
accumulation (n.): late 15c., from Latin accumulationem (nominative accumulatio) "a heaping up," noun of action from past participle stem of accumulare "to heap up, amass," from ad- "in addition" (see ad-) + cumulare "heap up," from cumulus "heap" (see cumulus).
accuracy (n.): 1660s, from accurate + -cy.
accurate (adj.): 1610s, "done with care," from Latin accuratus "prepared with care, exact, elaborate," past participle of accurare "take care of," from ad- "to" (see ad-) + curare "take care of" (see cure). The notion of doing something carefully led to that of being exact (1650s). Related: Accurately; accurateness.
accursed (adj.): also accurst, early 13c., acursede "lying under a curse," past participle adjective from obsolete verb acursen "pronounce a curse upon, excommunicate" (late 12c.), from a- intensive prefix + cursein (see curse (v.)). The extra -c- is 15c., mistaken Latinism. Weakened sense of "worthy of a curse" is from 1590s. Related: Accursedly; accursedness.
accusation (n.): late 14c., from Old French acusacion or directly from Latin accusationem (nominative accusatio), noun of action from past participle stem of accusare (see accuse).
accusative (n.): grammatical case whose primary function is to express destination or goal of motion, mid-15c., from Anglo-French accusatif, Old French acusatif, or directly from Latin (casus) accusativus "(case) of accusing," from accusatus, past participle of accusare (see accuse).

Translating Greek ptosis aitiatike "case of that which is caused," on similarity of Greek aitiasthai "accuse." Greek aitia is the root of both, and means both "cause" and "accusation," hence the confusion of the Romans. A more correct translation would have been casus causativus.
accusatory (adj.): c.1600, from Latin accusatorius, from accusare (see accuse).
accuse (v.): c.1300, "charge (with an offense, etc.), impugn, blame," from Old French acuser "to accuse, indict, reproach, blame" (13c.), earlier "announce, report, disclose" (12c.), or directly from Latin accusare "to call to account," from ad- "against" (see ad-) + causari "give as a cause or motive," from causa "reason" (see cause (n.)). Related: Accused; accusing; accusingly.
accused (n.): "person charged with a crime," 1590s, from past participle of accuse (v.).
accustom (v.): early 15c., from Old French acostumer (12c., Modern French accoutumer), from à "to" (see ad-) + costume (see costume (n.)). Related: Accustomed; accustoming.
accustomed (adj.): late 15c., "made customary, habitual," past participle adjective from accustom (v.).
ace (n.): c.1300, "one at dice," from Old French as "one at dice," from Latin as "a unit, one, a whole, unity;" also the name of a small Roman coin ("originally one pound of copper; reduced by depreciation to half an ounce" [Lewis]), perhaps originally Etruscan and related to Greek eis "one" (from PIE *sem- "one, as one"), or directly from the Greek word.

In English, it meant the side of the die with only one mark before it meant the playing card with one pip (1530s). Because this was the lowest roll at dice, ace was used metaphorically in Middle English for "bad luck" or "something of no value;" but as the ace is often the highest playing card, the extended senses based on "excellence, good quality" arose 18c. as card-playing became popular. Ace in the hole in the figurative sense of "concealed advantage" is attested from 1904, from crooked stud poker deals.

Meaning "outstanding pilot" dates from 1917 (technically, in WWI aviators' jargon, one who has brought down 10 enemy planes, though originally in reference to 5 shot down), from French l'ace (1915), which, according to Bruce Robertson (ed.) "Air Aces of the 1914-1918 War" was used in prewar French sporting publications for "top of the deck" boxers, cyclists, etc. Sports meaning of "point scored" (1819) led to that of "unreturnable serve" (1889).
ace (v.): "to score" (in sports), 1923, from ace (n.). This led in turn to the extended student slang sense of "get high marks" (1959). Related: Aced; acing.
Aceldama: late 14c., potter's field near Jerusalem purchased with the blood-money given to Judas Iscariot, literally "place of bloodshed," from Greek Akeldama, from an Aramaic phrase akin to Syriac haqal dema "the field of blood."
acephalous (adj.): "headless," 1731, from French acéphale + -ous, or directly from Late Latin acephalus, from Greek akephalos, from a- "not" + kephale "head" (see cephalo-).
acerbic (adj.): 1865, originally, and usually, figurative: "sour, harsh, severe" (of speech, manners, etc.), from Latin acerbus "harsh to the taste, sharp, bitter, sour" (see acerbity) + -ic.
acerbity (n.): 1570s, from Middle French acerbité, from Latin acerbitatem (nominative acerbitas) "harshness, sharpness, bitterness," from acerbus "bitter to taste, sharp, sour, tart" (related to acer "sharp;" cf. Latin superbus "haughty," from super "above"), from Proto-Italic *akro-po- "sharp," from PIE *ak- "sharp" (see acrid). Earliest use in English is figurative, of "sharp and bitter" persons. Of tastes, from 1610s.
acetaminophen (n.): U.S. name for "para-acetylaminophenol," 1960, composed of syllables from the chemical name; in Britain, the same substance is paracetamol.
acetate (n.): 1827, "salt formed by combining acetic acid with a base," from Latin acetum "vinegar" (see acetic) + chemical suffix -ate (3). As a type of synthetic material, it is attested from 1920, short for acetate silk, etc.
acetic (adj.): 1808, from French acétique "pertaining to vinegar," from Latin acetum "vinegar" (properly vinum acetum "wine turned sour;" see vinegar), originally past participle of acere "be sour," related to acer "sharp" (see acrid).
aceto-: before vowels acet-, word-forming element from comb. form of acetic and generally indicating compounds from or related to acetic acid.
acetone (n.): colorless volatile liquid, 1839, literally "a derivative of acetic acid," from Latin acetum "vinegar" (see acetic) + Greek-based chemical suffix -one, which owes its use in chemistry to this word.
acetylene (n.): gaseous hydrocarbon, 1864, from French acétylène, coined by French chemist Marcelin-Pierre-Eugène Berthelot (1823-1907) from chemical ending -ene + acetyl, which was coined from acetic in 1839 by German chemist Justus von Liebig; see acetic. Liebig's coinage was in reference to a different radical; acetyl was transferred to its current sense in 1850s, but Berthelot's coinage was based on the original use of acetyl.
The name acetylene is an unfortunate one as the hydrocarbon is not directly related to the modern acetyl radical and the molecule ... contains a triple bond, not a double bond which the suffix -ene (q.v.) implies. [Flood, "Origins of Chemical Names," 1963]
ach (interj.): aspirated form of ah; in English often used to represent German or Celtic speech.
Achates: armor-bearer and faithful friend of Aeneas in the "Aeneid," hence sometimes used figuratively for "faithful friend." The name is from Greek akhates "agate" (see agate).
ache (v.): Old English acan "to ache, suffer pain," from Proto-Germanic *akanan, perhaps from a PIE root *ag-es- "fault, guilt," represented also in Sanskrit and Greek, perhaps imitative of groaning. The verb was pronounced "ake," the noun "ache" (by i-mutation, as in speak/speech) but while the noun changed pronunciation to conform to the verb, the spelling of both was changed to ache c.1700 on a false assumption of a Greek origin (specifically Greek akhos "pain, distress," which is rather a distant relation of awe (n.)). Related: Ached; aching.
ache (n.): early 15c., æche, from Old English æce, from Proto-Germanic *akiz, from same source as ache (v.).
Acheron: 1580s, fabled river of the Lower World in Greek mythology. The name perhaps means "marsh-like" (cf. Greek akherousai "marshlike water"); the derivation from Greek akhos "woe" is considered folk etymology.
achieve (v.): early 14c., from Old French achever (12c.) "to finish, accomplish, complete," from phrase à chef (venir) "at an end, finished," or Vulgar Latin *accapare, from Late Latin ad caput (venire); both the French and Late Latin phrases meaning literally "to come to a head," from stem of Latin caput "head" (see capitulum).
The Lat. caput, towards the end of the Empire, and in Merov[ingian] times, took the sense of an end, whence the phrase ad caput venire, in the sense of to come to an end .... Venire ad caput naturally produced the Fr. phrase venir à chef = venir à bout. ... From this chief, O.Fr. form of chef (q.v.) in sense of term, end, comes the Fr. compd. achever = venir à chef, to end, finish. [Auguste Brachet, "An Etymological Dictionary of the French Language," transl. G.W. Kitchin, Oxford, 1878]
Related: Achieved; achieving.
achievement (n.): late 15c., "act of completing" (something), from Middle French achèvement "a finishing," noun of action from Old French achever (see achieve). Meaning "thing achieved" is recorded from 1590s.
Achilles: Greek hero of the Trojan War stories, son of Thetis and Peleus, his name is perhaps a compound of akhos "pain, grief" (see awe) + laos "the people, a people" (see lay (adj.)); or else it is from a pre-Greek language.