Old English efen "level," also "equal, like; calm, harmonious; equally; quite, fully; namely," from Proto-Germanic *ebna- (source also of Old Saxon eban, Old Frisian even "level, plain, smooth," Dutch even, Old High German eban, German eben, Old Norse jafn, Danish jævn, Gothic ibns). The adverb is Old English efne "exactly, just, likewise." Modern adverbial sense (introducing an extreme case of something more generally implied) seems to have arisen 16c. from use of the word to emphasize identity ("Who, me?" "Even you").
Etymologists are uncertain whether the original sense was "level" or "alike." Used extensively in Old English compounds, with a sense of "fellow, co-" (as in efeneald "of the same age;" Middle English even-sucker "foster-brother"). Of numbers, from 1550s. Sense of "on an equal footing" is from 1630s. Rhyming reduplication phrase even steven is attested from 1866; even break (n.) first recorded 1907. Even-tempered from 1712. To get even with "retaliate upon" is attested by 1833.
Old English efnan "to make even, to make level; liken, compare" (see even (adj.)). Intransitive sense of "become even" is attested from early 13c. Related: Evened; evening.
"that which is up," 1530s, from up (adv.). Phrase on the up-(and-up) "honest, straightforward" first attested 1863, American English.
Old English up, uppe, from Proto-Germanic *upp- "up" (source also of Old Frisian, Old Saxon up "up, upward," Old Norse upp; Danish, Dutch op; Old High German uf, German auf "up"; Gothic iup "up, upward," uf "on, upon, under;" Old High German oba, German ob "over, above, on, upon"), from PIE root *upo "under," also "up from under," hence also "over."
As a preposition, "to a higher place" from c. 1500; also "along, through" (1510s), "toward" (1590s). Often used elliptically for go up, come up, rise up, etc. Up the river "in jail" first recorded 1891, originally in reference to Sing Sing, which is up the Hudson from New York City. To drive someone up the wall (1951) is from the notion of the behavior of lunatics or caged animals. Insulting retort up yours (scil. ass) is attested by late 19c.
prefix with various senses, from Old English up (adv.), corresponding to similar prefixes in other Germanic languages.
1550s, "to drive and catch (swans)," from up (adv.). Intransitive meaning "get up, rise to one's feet" (as in up and leave) is recorded from 1640s. Sense of "to move upward" is recorded from 1737. Meaning "increase" (as in up the price of oil) is attested from 1915. Compare Old English verb uppian "to rise up, swell." Related: Upped; upping. Upping block, used for mounting or dismounting horses, carriages, etc., is attested from 1796 (earlier was horsing-block, 1660s).
c. 1300, "dwelling inland or upland," from up (adv.). Meaning "going up" is from 1784. From 1815 as "excited, exhilarated, happy," hence "enthusiastic, optimistic." Up-and-coming "promising" is from 1848. Musical up-tempo (adj.) is recorded from 1948.