Online Etymology Dictionary

Allah: 1702, Arabic name for the Supreme Being, from Arabic Allahu, contraction of al-Ilahu, from al "the" + Ilah "God," related to Hebrew Elohim.
allative (n.): grammatical case expressing "motion towards," 1860, from Latin allatus "brought to," used as past participle of adferre, affere "to bring to," from ad- "to" (see ad-) + latus "borne, carried" (see oblate (n.)).
allay (v.): Old English alecgan "to put down, remit, give up," a Germanic compound (cf. Gothic uslagjan, Old High German irleccan, German erlegen), from a- "down, aside" + lecgan "to lay" (see lay).

Early Middle English pronunciations of -y- and -g- were not always distinct, and the word was confused in Middle English with various senses of Romanic-derived alloy and allege, especially the latter in an obsolete sense of "to lighten," from Latin ad- "to" + levis (see lever).
Amid the overlapping of meanings that thus arose, there was developed a perplexing network of uses of allay and allege, that belong entirely to no one of the original vbs., but combine the senses of two or more of them. [OED]
The double -l- is 17c., a mistaken Latinism. Related: Allayed; allaying.
allegation (n.): early 15c., "action of alleging," from Middle French allégation, from Latin allegationem (nominative allegatio) "a sending, despatching," noun of action from past participle stem of allegare (see allege).
allege (v.): c.1300. It has the form of one French verb and the meaning of another. The form is Anglo-French aleger, Old French eslegier "to clear at law," from Latin ex- "out of" (see ex-) and litigare "bring suit" (see litigate); however eslegier meant "acquit, clear of charges in a lawsuit." It somehow acquired the meaning of French alléguer, from Latin allegare "send for, bring forth, name, produce in evidence," from ad- "to" (see ad-) + legare "to depute, send" (see legate). Related: Alleged; alleging.
alleged (adj.): mid-15c., "quoted," past participle adjective from allege. Attested from 1610s in sense of "brought forth in court;" 1670s as "asserted but not proved."
allegedly (adv.): 1828, from alleged + -ly (2).
alleger (n.): 1570s, agent noun from allege. The Latinate form, allegator (1680s) rarely was used, for some reason.
allegiance (n.): late 14c., from Anglo-French legaunce "loyalty of a liege-man to his lord," from Old French legeance, from liege (see liege); erroneously associated with Latin ligare "to bind;" corrupted in spelling by confusion with the now-obsolete legal term allegeance "alleviation." General figurative sense of "recognition of claims to respect or duty" is attested from 1732.
allegorical (adj.): 1520s, from French allégorique, from Latin allegoricus, from Greek allegorikos (see allegory). Earlier form was allegoric (late 14c.). Related: Allegorically.
allegory (n.): late 14c., from Old French allegorie (12c.), from Latin allegoria, from Greek allegoria "figurative language, description of one thing under the image of another," literally "a speaking about something else," from allos "another, different" (see alias) + agoreuein "speak openly, speak in the assembly," from agora "assembly" (see agora).
allegretto: 1740, from Italian allegretto, diminutive of allegro (q.v.).
allegro: 1680s as a musical term, from Italian allegro "cheerful, gay," from Latin alacrem (nominative alacer) "lively, cheerful, brisk" (see alacrity).
allele (n.): 1931, from German allel, abbreviation of allelomorph (1902), coined from Greek allel- "one another" (from allos "other;" see alias) + morphe "form" (see Morpheus).
alleluia: late 14c., from Latin alleluja, from Greek allelouia, from Hebrew hallelu-yah "praise Jehovah" (see hallelujah).
allemande (n.): a German dance, 1775, from French Allemande, fem. of allemand "German" (see Alemanni). As a move in country or square dancing, from 1808.
Allen: masc. proper name, variant of Alan (q.v.). In reference to wrench, key, screw, etc. with hexagonal socket or head, 1913, from the Allen Manufacturing Company of Hartford, Connecticut, U.S.
allergen (n.): substance causing allergy, 1912, from allergy on model of antigen.
allergic (adj.): 1911, from allergy + -ic; cf. French allergique (1906). Figurative use, "antipathetic, repulsed" is from 1936.
allergy (n.): 1911, from German Allergie, coined 1906 by Austrian pediatrician Clemens E. von Pirquet (1874-1929) from Greek allos "other, different, strange" (see alias (adv.)) + ergon "activity" (see urge (v.)).
alleviate (v.): late 15c., from Middle French allevier or directly from Late Latin alleviatus, past participle of alleviare "to lighten," from Latin ad- "to" (see ad-) + levis "light" in weight (see lever). Related: Alleviated; alleviating.
alleviation (n.): early 15c., from Middle French aleviacion or directly from Medieval Latin alleviationem (nominative alleviatio), noun of action from past participle stem of alleviare (see alleviate).
alley (n.): mid-14c., "passage in a house; open passage between buildings; walkway in a garden," from Old French alee (13c., Modern French allée) "a path, passage, way, corridor," also "a going," from fem. of ale, past participle of aler "to go," which ultimately may be a contraction of Latin ambulare "to walk," or from Gallo-Romance allari, a back-formation from Latin allatus "having been brought to" [Barnhart]. Cf. sense evolution of gate. Applied by c.1500 to "long narrow enclosure for playing at bowls, skittles, etc." Used in place names from c.1500.

The word is applied in American English to what in London is called a mews, and also is used there especially of a back-lane parallel to a main street (1729). To be up someone's alley "in someone's neighborhood" (literally or figuratively) is from 1931; alley-cat attested by 1890.
alley-way (n.): 1788, from alley + way.
alliance (n.): c.1300, "bond of marriage" (between ruling houses or noble families), from Old French aliance (12c., Modern French alliance) "alliance, bond; marriage, union," from aliier (Modern French allier) "combine, unite" (see ally (v.)). As a bond or treaty between rulers, late 14c.
allied (adj.): c.1300, past participle adjective from ally (v.). Originally of kindred; in reference to a league or formal treaty, it is first recorded late 14c.
alligator (n.): 1560s, lagarto (modern form attested from 1620s, with excrescent -r as in tater, feller, etc.), a corruption of Spanish el lagarto (de Indias) "the lizard (of the Indies)," from Latin lacertus (see lizard). Alligarter was an early variant. The slang meaning "non-playing devotee of swing music" is attested from 1936; the phrase see you later, alligator is from a 1956 song title.
Allison: fem. proper name, a diminutive of Alice (q.v.), via Old French Alison. Popular in U.S. as a girl's name from 1990s, but all but unknown there before 1946; it was popular in England and Scotland 13c.-17c. As a surname, it could represent "Alice's son."
alliterate (v.): "to use alliteration," 1776 (implied in alliterated), back-formation from alliteration, on analogy of obliterate. Related: Alliterating.
alliteration (n.): 1650s, "a begining with the same letter," from Modern Latin alliterationem (nominative alliteratio), noun of action from past participle stem of alliterare "to begin with the same letter," from Latin ad- "to" (see ad-) + littera (also litera) "letter, script" (see letter). Formed on model of obliteration, etc. Related: Alliterational.
alliterative (adj.): 1764, from alliterate + -ive. Related: Alliteratively.
allo-: word-forming element meaning "other," from Greek allo-, comb. form of allos "other, different" (see alias (adv.)).
allocate (v.): 1630s, from verbal used of adjective allocate (mid-15c. in legal use), from Medieval Latin allocate (the common first word of writs authorizing payment), imperative plural of allocare "allocate," from Latin ad- "to" (see ad-) + locare "to place" (see locate). Related: Allocated; allocating.
allocation (n.): mid-15c., from Middle French allocacion, from Medieval Latin allocationem (nominative allocatio), noun of action from past participle stem of allocare (see allocate).
allogenic (adj.): 1888, from Greek allogenes "of another race, stranger," from allos "other, different" (see allo-) + -genes "born" (see -gen) + -ic.
allograph (n.): "writing made by another person," by 1916 (implied in allographic), from allo- + -graph "something written," from Greek graphe "writing," from graphein "to write, express by written characters," earlier "to draw, represent by lines drawn" (see -graphy).
allons: "well!" French, literally "let us go," first person plural imperative of aller "to go."
allopath (n.): 1830, back-formation from allopathy.
allopathic (adj.): 1830, from French allopathique (see allopathy). Related: Allopathically.
allopathy (n.): 1842, "treatment of disease by remedies that produce effects opposite to the symptoms," from German Allopathie (Hahnemann), from Greek allos "other" (see alias) + -patheia, "suffering, disease, feeling" (see -pathy). The term applied by homeopathists to traditional medicine.
allot (v.): late 15c., from Old French aloter (Modern French allotir) "to divide by lots, to divide into lots," from à "to" (see ad-) + loter "lot," a word of Germanic origin (cf. Gothic hlauts, Old High German hloz, Old English hlot; see lot). Related: Allotted; allotting.
allotment (n.): 1570s, "action of allotting," from Middle French allotement, from Old French aloter (see allot). Or else a native formation from allot + -ment. Meaning "portion assigned to someone or some purpose" is from 1670s.
allotrope (n.): 1847, back-formation from allotropy "variation of physical properties without change of substance," from allo- + -tropy "manner" (see -trope). Related: Allotropic.
allow (v.): early 14c., allouen, "to commend, praise; approve of, be pleased with; appreciate the value of;" also, "take into account or give credit for," also, in law and philosophy, "recognize, admit as valid" (a privilege, an excuse, a statement, etc.). From late 14c. as "sanction or permit; condone;" in business use from early 15c.

The Middle English word is from Anglo-French alouer, Old French aloer, alloiier (13c.) "allot, apportion, bestow, assign," from Latin allocare (see allocate). This word in Old French was confused and ultimately merged with aloer; alloer "to praise, commend," from Latin allaudare, adlaudare, compound of ad- "to" (see ad-) + laudare "to praise" (see laud). From the first word came the sense preserved in allowance as "money granted;" from the second came its meaning "permission based on approval."
Between the two primary significations there naturally arose a variety of uses blending them in the general idea of assign with approval, grant, concede a thing claimed or urged, admit a thing offered, permit, etc., etc. [OED].
Related: Allowed; allowing.
allowable (adj.): late 14c., from Old French allouable, from allouer (see allow).
allowance (n.): late 14c., "praise" (a sense now obsolete), from Old French aloance "allowance, granting, allocation," from alouer (see allow). Sense of "a sum alloted to meet expenses" is from c.1400. In accounts, meaning "a sum placed to one's credit" is attested from 1520s. To make allowances is literally to add or deduct a sum from someone's account for some special circumstance. Figurative use of the phrase is attested from 1670s.
allowed (adj.): late 14c., "praised;" mid-15c., "assigned as a due share;" late 15c., "permitted," past participle adjective from allow.
alloy (n.): early 14c. "relative freedom of a noble metal from alloy or other impurities," from Anglo-French alai, Old French aloi, from aloiier (see alloy (v.)). Meaning " base metal alloyed with a noble metal" is from c.1400. Modern spelling from late 17c.
alloy (v.): c.1400, "mix with a baser metal," from Old French aloiier "assemble, join," from Latin alligare "bind to, tie to," compound of ad- "to" (see ad-) + ligare "to bind" (see ligament); hence "bind one thing to another." Related: Alloyed; alloying.
allright: see alright.