Online Etymology Dictionary

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."
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, from allopathie (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 (adv.)) + -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 (cognates: 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.
allspice (n.): spice made from the berry of the Jamaican pimento, 1620s, from all + spice (n.), "so called because supposed to combine the flavour of cinnamon, nutmeg, and cloves" [Weekley].
allude (v.): 1530s, "mock," from Middle French alluder or directly from Latin alludere "to play, sport, joke, jest," from ad- "to" (see ad-) + ludere "to play" (see ludicrous). Meaning "make an indirect reference, point in passing" is from 1570s. Related: Alluded; alluding.
allure (v.): c. 1400, from Anglo-French alurer, Old French aleurer "to attract, captivate; train a falcon to hunt," from à "to" (see ad-) + loirre "falconer's lure," from a Frankish word (see lure), perhaps influenced by French allure "gait, way of walking." Related: Allured; alluring. The noun is first attested 1540s; properly this sense is allurement.
allurement (n.): 1540s, "means of alluring;" see allure (v.) + -ment. Meaning "act of alluring" is recorded from 1560s.
alluring (n.): 1530s, "action of attracting," verbal noun from allure (v.).
alluring (adj.): "appealing to desires," 1570s, present participle adjective from allure (v.). Related: Alluringly.
allusion (n.): 1540s, from Latin allusionem (nominative allusio) "a playing with, a reference to," noun of action from past participle stem of alludere (see allude). An allusion is never an outright or explicit mention of the person or thing the speaker seems to have in mind.
allusive (adj.): c. 1600, from Latin allus-, past participle stem of alludere (see allude) + -ive. Related: Allusively; allusiveness.
alluvial (adj.): 1802, from Latin alluvius "alluvial" (see alluvium) + -al (1).
alluvium (n.): "matter deposited by flowing water," 1660s, from Medieval Latin alluvium, neuter of alluvius "washed against," from Latin alluere "wash against," from ad- "to, against" (see ad-) + -luere, comb. form of lavere "to wash" (see lave).
ally (v.): late 13c., "to join in marriage," from Old French alier "combine, unite," from a differentiated stem of aliier (from Latin alligare "bind to;" see alloy). Meaning "to form an alliance, join, associate" is late 14c. Related: allied; allying.
ally (n.): late 14c., "relative, kinsman," from ally (v.); mid-15c. in the sense of "one united with another by treaty or league."
Alma: fem. proper name, from Latin Alma "nourishing," fem. of almus; from alere "to nourish" (see old).
Alma Mater (n.): late 14c., Latin, literally "bountiful mother," a title Romans gave to goddesses, especially Ceres and Cybele, from alma, fem. of almus "nourishing," from alere "to nourish" (see old) + mater "mother" (see mother (n.1)). First used 1710 in sense of "one's university or school" in reference to British universities.
almagest (n.): late 14c., title of a treatise on astronomy by Claudius Ptolemy of Alexandria, extended in Middle English to other works on astrology or astronomy, from Old French almageste (13c.), from Arabic al majisti, from al "the" + Greek megiste "the greatest (composition)," from fem. of megistos, superlative of megas "great" (see mickle). Originally titled in Greek Megale syntaxis tes astronomias "Great Composition on Astronomy;" Arab translators in their admiration altered this.
almah (n.): Egyptian dancing-girl, belly-dancer, 1814, perhaps from Arabic almah (fem. adjective), "learned, knowing," from alama "to know." Or perhaps from a Semitic root meaning "girl" (source also of Hebrew alma "a young girl, a damsel").
almanac (n.): late 14c., attested in Anglo-Latin from mid-13c., via Old French almanach or directly from Medieval Latin almanachus, which is of uncertain origin. It is sometimes said to be from a Spanish-Arabic al-manakh "calendar, almanac" but possibly ultimately from Late Greek almenichiakon "calendar," which itself is said to be of Coptic origin. This word has been the subject of much speculation. Originally a book of permanent tables of astronomical data; one-year versions, combined with ecclesiastical calendars, date from 16c.; "astrological and weather predictions appear in 16-17th c.; the 'useful statistics' are a modern feature" [OED].
almighty (adj.): Old English ælmihtig "all-powerful," also a by-name of God; compound of æl (see all) + mihtig (see mighty); common Germanic (cognates: Old Saxon alomahtig, Old High German alamahtic, German allmächtig, Old Norse almattigr), perhaps an early Germanic loan-translation of Latin omnipotens (see omnipotent).
The almighty dollar, that great object of universal devotion throughout our land. [Washington Irving, 1836]
Related: Almightily.
Almohades: 12c. Muslim religious power that ruled Spain and North Africa, founded by Mohammed ibn Abdullah, the name is literally "the Unitarians," short for Arabic al-muwahhidun "they who profess the unity (of God)," so called for their absolutist monotheism.
almond (n.): c. 1300, from Old French almande, amande, from Vulgar Latin *amendla, *amandula, from Latin amygdala (plural), from Greek amygdalos "an almond tree," which is of unknown origin, perhaps a Semitic word. Altered in Medieval Latin by influence of amandus "loveable," and acquiring in French an excrescent -l- perhaps from Spanish almendra "almond," which got it via confusion with the Arabic definite article al-, which formed the beginnings of many Spanish words. Applied to eyes shaped like almonds, especially of certain Asiatic peoples, from 1870.
almoner (n.): "official distributor of alms on behalf of another," c. 1300 (mid-13c. as a surname), from Old French almosnier (12c.; Modern French aumônerie), from Vulgar Latin *almosinarius, from Late Latin elemosinarius (adj.) "connected with alms," from eleemosyna "alms" (see alms).
Almoravides: Muslim Berber horde from the Sahara which founded a dynasty in Morocco (11c.) and conquered much of Spain and Portugal. The name is Spanish, from Arabic al-Murabitun, literally "the monks living in a fortified convent," from ribat "fortified convent."
almost (adv.): Old English eallmæst "nearly all, for the most part," literally "mostly all;" see all + most. Modern form from 15c.
alms (n.): Old English ælmesse "alms, almsgiving," from Proto-Germanic *alemosna (source also of Old Saxon alamosna, Old High German alamuosan, Old Norse ölmusa), an early borrowing of Vulgar Latin *alemosyna (source of Old Spanish almosna, Old French almosne, Italian limosina), from Church Latin eleemosyna (Tertullian, 3c.), from Greek eleemosyne "pity, mercy," in Ecclesiastical Greek "charity, alms," from eleemon "compassionate," from eleos "pity, mercy," which is of unknown origin, perhaps imitative of cries for alms. Spelling perversion in Vulgar Latin is perhaps by influence of alimonia.
almshouse (n.): mid-15c., from alms + house (n.).
aloe (n.): Old English alewe "fragrant resin of an East Indian tree," a Biblical usage, from Latin aloe, from Greek aloe, translating Hebrew ahalim (plural, perhaps ultimately from a Dravidian language).

The Greek word probably was chosen for resemblance of sound to the Hebrew, because the Greek and Latin words referred originally to a genus of plants with spiky flowers and bitter juice, used as a purgative drug, a sense which appeared in English late 14c. The word was then misapplied to the American agave plant in 1680s. The "true aloe" consequently is called aloe vera.
aloft (adv.): c. 1200, from a Scandinavian source such as Old Norse a lopti "up above," literally "up in the air," from a "in, on" + lopt "sky, air, atmosphere; loft, upper room," from the general Germanic word for "air" (cognate with Gothic luftus, Old High German luft, Old English lyft "air;" see loft (n.)).
aloha: 1798, Hawaiian aloha, Maori aroha, an expression used in greeting or valediction, literally "love, affection, pity." Sometimes aloha 'oe, from 'oe "to you."
alone (adj., adv.): c. 1300 contraction of all ane, from Old English all ana "unaccompanied, all by oneself," from all "all, wholly" (see all) + an "one" (see one). Similar compounds are found in German (allein) and Dutch (alleen).
along (prep.): Old English andlang "entire, continuous; extended; all day long; alongside of," from and- "opposite, against" (from Proto-Germanic *andi-, *anda-, from PIE *anti "against," locative singular of *ant- "front, forehead;" see ante) + lang "long" (see long (adj.)). Sense extended to "through the whole length of."
alongshore (adj.): 1779, from along + shore (n.).