"in bed," c. 1200, contraction of Old English on bedde "in bed," from a- (1) + dative of bed (n.).

c. 1200, "toward the rear," a contraction of Old English on bæc "backward, behind, at or on the back;" see a- (1) + back (n.). Now surviving mainly in taken aback, which originally was a nautical expression in reference to a vessel's square sails when a sudden change of wind flattens them back against the masts and stops the forward motion (1754). The figurative sense from this, "suddenly or unexpectedly checked or disappointed," is by 1792.

"remission, forgiveness," c. 1200, from Old French absolucion, earlier assolucion, from Latin absolutionem (nominative absolutio) "completion, acquittal," noun of action from past-participle stem of absolvere "set free, loosen, acquit," from ab "off, away from" (see ab-) + solvere "to loosen, dissolve; untie, release; dismiss," from PIE *se-lu-, from reflexive pronoun *s(w)e- (see idiom) + root *leu- "to loosen, divide, cut apart." Originally of sins; in general use from c. 1400.

c. 1200, o cros, "in the shape of a cross;" c. 1300, a-croiz, "in a crossed position;" early 14c., acros, "from one side to another;" a contraction of Anglo-French an cros, literally "on cross;" see a- (1) + cross (n.)).

Meaning "on the other side (as a result of crossing)" is from 1750. In crossword puzzle clues from 1924. Spelling acrost, representing a dialectal or vulgar pronunciation, is attested by 1759. Phrase across the board "embracing all categories" (1945) is said to be originally from horse-racing, in reference to a bet of the same amount of money on a horse to win, place, or show. To get (something) across "make (something) understood or appreciated" is by 1913, probably from earlier theater expression get (something) across the footlights, perform it so as to be received by the audience (1894).

c. 1200, "made of adamant; having the qualities of adamant" (hard, unyielding, unbreakable, inflexible), from Latin adamantinus "hard as steel, inflexible," from Greek adamantinos "hard as adamant," from adamas (genitive adamantos) "unbreakable, inflexible," as a noun, "hardest material" (see adamant (n.)).

c. 1200, amiral, admirail, "Saracen commander or chieftain," from Old French amirail (12c.) "Saracen military commander; any military commander," ultimately from medieval Arabic amir "military commander," probably via Medieval Latin use of the word for "Muslim military leader."

Amiral de la mer "commander of a fleet of ships" is in late 13c. Anglo-French documents. Meaning "highest-ranking naval officer" in English is from early 15c. The extension of the word's meaning from "commander on land" to "commander at sea" likely began in 12c. Sicily with Medieval Latin amiratus and then spread to the continent, but the word also continued to mean "Muslim military commander" in Europe in the Middle Ages. The Arabic word was later Englished as emir.

As amīr is constantly followed by -al- in all such titles, amīr-al- was naturally assumed by Christian writers as a substantive word, and variously Latinized .... [OED]

Also in Old French and Middle English the word was further conformed to familiar patterns as amirauld, amiraunt. The unetymological -d- probably is from influence of Latin ad-mirabilis (see admire). Italian form almiraglio, Spanish almirante are from confusion with Arabic words in al-. As the name of a type of butterfly from 1720, according to OED possibly a corruption of admirable.

c. 1200, aventure, auenture "that which happens by chance, fortune, luck," from Old French aventure (11c.) "chance, accident, occurrence, event, happening," from Latin adventura (res) "(a thing) about to happen," from fem. of adventurus, future participle of advenire "to come to, reach, arrive at." This is from ad "to" (see ad-) + venire "to come" (from a suffixed form of PIE root *gwa- "to go, come").

The meaning developed through "risk; danger" (a trial of one's chances), c. 1300, and "perilous undertaking" (late 14c.) to "novel or exciting incident, remarkable occurrence in one's life" (1560s).

Earlier it also meant "a wonder, a miracle; accounts of marvelous things" (13c.). The -d- was restored in English 15c.-16c.; in French the attempt to restore it at about the same time was rejected. Venture is a 15c. variant. German Abenteuer is a borrowing of the French word, apparently deformed whimsically by influence of Abend "evening."

c. 1200, aduersite "condition of misfortune, hardship, difficulty, distress," from Old French adversite, aversite "adversity, calamity, misfortune; hostility, wickedness, malice" (Modern French adversité), from Latin adversitatem (nominative adversitas) "opposition," from adversus "turned against, hostile" (see adverse).

c. 1200, affeccioun, "desire, inclination, wish, intention;" mid-14c., "an emotion of the mind, passion, lust as opposed to reason;" from Old French afection (12c., Modern French affection) "emotion, inclination, disposition; love, attraction, enthusiasm," from Latin affectionem (nominative affectio) "a relation, disposition; a temporary state; a frame, constitution," noun of state from past-participle stem of afficere "to do something to, act on," from ad "to" (see ad-) + facere (past participle factus) "to make, do" (from PIE root *dhe- "to set, put").

The sense developed in Latin from "disposition" to "good disposition, zealous attachment." In English the sense of "love" is from late 14c. Formally it goes with affect (v.2), but it has absorbed some sense from (v.1). Related: Affections.

"on fire," c. 1200, afure, from a- (1) "on" + fire (n.). Figurative use by late 14c.