Online Etymology Dictionary

ass (1): beast of burden, O.E. assa (Old Northumbrian assal, assald), prob. from O.Celt. *as(s)in "donkey," which (with Ger. esel, Goth. asilus, Lith. asilas, O.C.S. osl) is ultimately from L. asinus, probably of Middle Eastern origin (cf. Sumerian ansu). Since ancient Gk. times, in fables and parables, the animal typifies clumsiness and stupidity (hence asshead, 1540s, etc.). To make an ass of oneself is from 1580s. Asses' Bridge (c.1780), from L. Pons Asinorum, is fifth proposition of first book of Euclid's "Elements."
ass (2): slang for "backside," first attested 1860 in nautical slang, in popular use from 1930; chiefly U.S.; from dial. variant pronunciation of arse (q.v.). The loss of -r- before -s- attested in several other words (e.g. burst/bust, curse/cuss, horse/hoss, barse/bass). Indirect evidence of the change from arse to ass can be traced to 1785 (in euphemistic avoidance of ass "donkey" by polite speakers) and perhaps to Shakespeare, if Nick Bottom transformed into a donkey in "A Midsummer Night's Dream" (1594) is the word-play some think it is. Meaning "woman regarded as a sexual object" is from 1942.
assail: early 13c., from O.Fr. assailir (12c.), from V.L. *adsalire "to leap at," from L. ad- "at" + salire "to leap" (see salient).
assailant (n.): 1530s, from Fr. assailant, prp. (also used as a noun) of assailir (see assail).
assassin: 1530s (in Anglo-L. from mid-13c.), via Fr. and It., from Arabic hashishiyyin "hashish-users," pl. of hashishiyy, from hashish (q.v.). A fanatical Ismaili Muslim sect of the time of the Crusades, under leadership of the "Old Man of the Mountains" (translates Arabic shaik-al-jibal, name applied to Hasan ibu-al-Sabbah), with a reputation for murdering opposing leaders after intoxicating themselves by eating hashish. The pl. suffix -in was mistaken in Europe for part of the word (cf. Bedouin).
assassinate (v.): 1610s, from pp. stem of M.L. assassinare (see assassin). Of reputations, characters, etc., from 1620s.
assassination: c.1600, noun of action from assassinate (q.v.).
assault (n.): c.1300, from O.Fr. asaut (12c., Mod.Fr. assaut), from V.L. *adsaltus "attack, assault," from ad "to" + L. saltus "a leap," from salire "to leap, spring" (see assail). The verb is from c.1450.
assay (v.): early 14c., from Anglo-Fr. assaier, from assai (n.), from O.Fr. essai "trial" (see essay).
assemblage: c.1704, from Fr. assemblage "gathering, assemblage," from assembler (see assemble).
assemble: mid-13c. (trans.), c.1300 (intrans.), from O.Fr. assembler (11c.), from L. assimulare "to make like, think like," later "to gather together," from ad- "to" + simulare "to make like" (see simulation). In 14c. it also was a euphemism for "to couple sexually." Assemble together is redundant. Meaning "to put parts together" in manufacturing is from 1852.
assembly: early 14c., "a gathering of persons," from O.Fr. as(s)emblee, noun from fem. pp. of assembler "to assemble" (see assemble). Meaning "gathering together" is recorded from early 15c.; that of "act of assembling parts or objects" is from 1914, as is assembly line. School sense is recorded from 1932.
assent (v.): c.1300, from O.Fr. assentir (12c.), from L. assentare "to agree with," freq. of assentire, from ad- "to" + sentire "to feel, think" (see sense). The noun is c.1300, from O.Fr. assent, a back-formation from assentir.
assert: c.1600, "to declare," from L. assertus, pp. of asserere "to claim, maintain, affirm" (see assertion). To assert oneself "stand up for one's rights" is recorded from 1879.
assertion: early 15c., from O.Fr. assertion (14c.), from L.L. assertionem (nom. assertio), noun of action from L. asserere "claim rights over something, state, maintain, affirm," from ad- "to" + serere "join" (see series). By "joining oneself" to a particular view, one "claimed" or "maintained" it.
assertive: 1560s, "declaratory, positive, full of assertion," from assert + -ive. Meaning "insisting on one's rights" is short for self-assertive (1865). Assertiveness "tendency toward self-assertion" is from 1881.
assess: early 15c., "to fix the amount (of a tax, fine, etc.)," from Anglo-Fr. assesser, from M.L. assessare "fix a tax upon," originally frequentative of L. assessus, pp. of assidere "to sit beside" (and thus to assist in the office of a judge), from ad- "to" + sedere "to sit." One of the judge's assistant's jobs was to fix the amount of a fine or tax. Meaning "to estimate the value of property for the purpose of taxing it" is from 1809; transf. sense of "to judge the value of a person, idea, etc." is from 1934.
assessment: c.1540, "value of property for tax purposes," from assess + -ment. Meaning "determination or adjustment of tax rate" is from 1540s; general sense of "estimation" is recorded from 1620s.
assessor: late 14c., from O.Fr. assessour (12c., Mod.Fr. assesseur), from L. assessorem "an assistant judge," in L.L. "one who assesses taxes," agent noun from assidere (see assess).
asset: see assets.
assets: 1530s, from Anglo-Fr. asetz (singular), from O.Fr. assez "enough" (11c.), from V.L. *ad satis "to sufficiency," from L. ad- "to" + satis "enough" (see sad). Beginning as a legal term, "sufficient estate" (to satisfy debts and legacies), it passed into general use; meaning "any property that theoretically can be converted to ready money" is from 1580s. Asset is a 19c. artificial singular.
asseverate: 1791, from L. asseveratus, pp. of asseverare "to assert seriously," from ad- "to" + severus "serious, severe" (see severe).
asseveration: 1550s, from L. asseverationem (nom. asseveratio) "vehement assertion," from asseveratus, pp. of asseverare "to swear solemnly, act with earnestness, assert strongly," from ad- "to" + severus "strict, severe" (see severe).
asshole: "contemptible person," mid-1930s. In O.E., Latin anus was glossed with earsðeri.
assiduity: c.1600, from L. assiduatem "continual presence," noun of quality from assiduus (see assiduous).
assiduous: 1530s, from L. assiduus "busy, incessant, continual, constant," from assidere "to sit down to," thus "constantly occupied" at one's work; from ad "to" + sedere "to sit" (see sedentary). The word acquired a taint of "servility" in 18c.
assiento: 1714, "contract between the King of Spain and another power" (esp. that made at the Peace of Utrecht, 1713, with Great Britain for furnishing African slaves to the Sp. colonies in the Americas), from Sp. asiento, from asentar "to adjust, settle, establish," lit. "to place on a chair," from a sentar, from L. sedens, prp. of sedere "to sit" (see sedentary).
assign: c.1300, from O.Fr. assigner (13c.), from L. assignare "to mark out, to allot by sign," from ad- "to" + signare "make a sign," from signum "mark" (see sign). Main original use was in Eng. law, in transferences of personal property. General meaning "to fix, settle, determine, appoint" is from c.1300.
assignation: c.1400, "appointment by authority," from O.Fr. assignacion (14c., Mod.Fr. assignation), from L. assignationem "allotment," noun of action from assignare (see assign). Meaning "action of legally transfering" (a right or property) is from 1570s; that of "a meeting by arrangement, tryst" is from 1650s.
assignee: early 15c., "one who is appointed to act for another," from O.Fr. assigne, pp. of assigner (see assign).
assignment: late 14c., "appointment," from O.Fr. assignment, from L.L. assignamentum, noun of action from assignare (see assign). Meaning "a task assigned" (to someone) is from c.1848.
assimilate: 1520s, from L. assimilatus, pp. of assimilare "to make like," from ad- "to" + simulare "make similar," from similis "like, resembling" (see similar). Originally trans. (with to); intrans. use first recorded 1837.
assimilation: c.1600, "act of assimilating," from L. assimilationem "likeness, similarity," noun of action from assimilatus, pp. of assimilare (see assimilate). Psychological sense is from 1855.
assimilationist: 1928, "one who advocates racial integration;" see assimilate.
assist (v.): early 15c., from M.Fr. assister "to stand by, help, put, place, assist" (14c.), from L. assistere "assist, stand by," from ad- "to" + sistere "take a stand, cause to stand," from PIE *siste-, reduplicated form of base *sta- "to stand" (see stet). Sporting sense (n.) is attested 1877 in baseball, 1925 in ice hockey.
assistance: late 14c., "act of helping or aiding," from O.Fr. assistance, from assister (see assist).
assistant: 1540s, "one who helps another," from pp. adj. (c.1400), from O.Fr. assistant (adj. and n.), lit. prp. of assister, from L. assistantem, prp. of assistare (see assist).
assize: c.1300 (attested from mid-12c. in Anglo-L.), from O.Fr. asise "session" (12c.), from fem. pp. of asseoir "to cause to sit," from L. assidere (see assess). Originally "all legal proceedings of the nature of inquests or recognitions;" hence sessions held periodically in each Eng. county to administer civil and criminal justice.
associate (v.): late 14c., from L. associatus pp. of associare "join with," from ad- "to" + sociare "unite with," from socius "companion." The noun is first recorded 1530s, from associate (adj.).
association: 1530s, "action of coming together," from L. associationem, noun of action from associatus, pp. of associare (see associate). Meaning "a body of persons with a common purpose" is from 1650s. Meaning "mental connection" is from 1680s; that of "quality or thing called to mind by something else" is from 1810.
associative: 1812, from associate (v.) + -ive.
assonance: 1727, "resemblance of sounds between words," from Fr. assonance, from assonant, from L. assonantem (nom. assonans), prp. of assonare "respond to," from ad- "to" + sonare "to sound" (see sound (n.1)). Properly, in prosody, "rhyming of accented vowels, but not consonants" (1823).
assort: late 15c., "to distribute into groups," from M.Fr. assortir (15c.), from O.Fr. assorter "to assort, match," from a- "to" + sorte "kind" (see sort).
assorted: "arranged in sorts," 1797, pp. adj. from assort (q.v.).
assortment: 1610s, "action of assorting," from assort + -ment. Sense of "group of things of the same sort" is attested from 1759; that of "group of things whether the same sort or not" from 1791.
assuage: c.1300, from O.Fr. assouagier "alleviate, calm, soothe, pacify," from V.L. *adsuaviare, from L. ad- "to" + suavis "sweet, agreeable" (see sweet).
assume: mid-15c., "to receive up into heaven" (especially of the Virgin Mary, e.g. Feast of the Assumption, celebrated Aug. 15, attested from c.1300), from L. assumere "to take up," from ad- "to, up" + sumere "to take," from sub "under" + emere "to take" (see exempt). Early pp. was assumpt. Meaning "to suppose" is first recorded 1590s. In rhetorical usage, assume expresses what the assumer postulates, often as a confessed hypothesis; presume expresses what the presumer really believes.
assumption: c.1300, "the reception, uncorrupted, of the Virgin Mary into Heaven," from L. assumptionem (nom. assumptio) "a taking, receiving," noun of action from assumptus, pp. of assumere (see assume). Meaning "action of taking for oneself" is recorded from 1580s; that of "something taken for granted" is from 1620s.
assumptive: 1610s, from L. assumptivus, from assumptus, pp. of assumere (see assume).
assurance: late 14c., "certainty," from O.Fr. asseurance (11c., Mod.Fr. assurance) "assurance, promise, truce, certainty," from asseurer (see assure). Meaning "promise, pledge" in Eng. is from late 14c. The word had a negative tinge 18c., often suggesting impudence or presumption.