late 14c., "to settle a dispute, determine a controversy," from Old French decider, from Latin decidere "to decide, determine," literally "to cut off," from de "off" (see de-) + caedere "to cut" (from PIE root *kae-id- "to strike"). For Latin vowel change, see acquisition. Sense is of resolving difficulties "at a stroke." Meaning "to make up one's mind" is attested from 1830. Related: Decided; deciding.
final letter of the Greek alphabet, c. 1400, from Medieval Greek omega, from classical Greek o mega "big 'o' " (in contrast to o micron "little 'o' "); so called because the vowel was long in ancient Greek. From o + megas "great, large, vast, big, high, tall; mighty, important" (from PIE root *meg- "great"). Used figuratively for "the last, the final" of anything (as in Revelation i.8) from 1520s.
1880, "suggested by the Editor" (OED editor Sir James A.H. Murray) for "gradual and unintentional loss of a short unaccented vowel at the beginning of a word" [OED], as squire from esquire, venture from adventure. With -ic + aphesis (1880), from Greek aphienai "to let go, to send forth," from assimilated form of apo "from" (see apo-) + hienai "to send, throw" (from PIE root *ye- "to throw, impel"). Compare apheresis.
1620s, "lasting for two years;" 1750, "occurring every two years," from Latin biennium "two-year period," from bi- "two" (see bi-) + annus "year" (see annual (adj.)). The vowel change is "due to the Latin phonetic law according to which the unaccented and closed radical syllable of the second element of compounds, original -ă- becomes -ĕ-" [Klein]. The noun meaning "a biennial plant" (which requires two seasons of growth to produce flowers and fruit and dies the next) is attested by 1770. Related: Biennially.
mid-15c., "property acquired other than by inheritance" (c. 1300 in Anglo-Latin), from Medieval Latin perquisitum "thing gained, profit," in classical Latin, "thing sought after," noun use of neuter past participle of perquirere "to seek, ask for," from per "thoroughly" (see per) + quærere "to seek" (see query (v.)). For Latin vowel change, see acquisition. The general meaning "any incidental profit, gain, or fee on top of regular wages" is by 1560s.
Old English feond "enemy, foe, adversary," originally present participle of feogan "to hate," from Proto-Germanic *fijand- "hating, hostile" (source also of Old Frisian fiand "enemy," Old Saxon fiond, Middle Dutch viant, Dutch vijand "enemy," Old Norse fjandi, Old High German fiant, Gothic fijands), from suffixed form of PIE root *pe(i)- "to hurt" (source also of Sanskrit pijati "reviles, scorns;" Avestan paman-, name of a skin disease; Greek pema "disaster, sorrow, misery, woe;" Gothic faian "to blame").
As spelling suggests, the word originally was the opposite of friend (n.). Both are from the active participles of the Germanic verbs for "to love" and "to hate." Boutkan says the "fiend" word was a Germanic analogical formation from the "friend" word. According to Bammesberger ["English Etymology"], "The long vowel in FIEND is regular. In FRIEND the vowel has been shortened; perhaps the shortening is due to compounds like FRIENDSHIP, in which the consonant group (-nds-) regularly caused shortening of the preceeding long vowel."
Fiend at first described any hostile enemy (male and female, with abstract noun form feondscipe "fiendship"), but it began to be used in late Old English for "the Devil, Satan" (literally "adversary") as the "enemy of mankind," which shifted its sense to "diabolical person" (early 13c.). The old sense of the word devolved to foe, then to the imported word enemy. For spelling with -ie- see field. Meaning "devotee (of whatever is indicated)," as in dope fiend, is from 1865.
late 14c., "act of obtaining," from Old French acquisicion "purchase, acquirement" (13c., Modern French acquisition) or directly from Latin acquisitionem (nominative acquisitio), noun of action from past-participle stem of acquirere "get in addition, accumulate," from ad "to," here perhaps emphatic (see ad-), + quaerere "to seek to obtain" (see query (v.)). Meaning "thing obtained" is from late 15c. The vowel change of -ae- to -i- in Latin is due to a phonetic rule in that language involving unaccented syllables in compounds.