What's the "een" in Halloween?
Old English up, uppe, from Proto-Germanic *upp- "up" (cf. Old Frisian up; Old Norse upp; Danish, Dutch op; Old High German uf, German auf "up"; Gothic iup "up, upward," uf "on, upon, under;" OHG oba, German ob "over, above, on, upon"), from PIE root *upo "up from below" (cf. Sanskrit upa "near, under, up to, on," Greek hypo "under, below," Latin sub "under;" see sub-).
Meaning "exhilarated, happy" first attested 1815. Musical up tempo (adj.) is recorded from 1948. Up-and-coming "promising" is from 1848. Phrase on the up-(and-up) "honest, straightforward" first attested 1863, American English. 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) attested by late 19c.
earliest recorded sense is "to drive and catch (swans)," 1560, from up (adv.). Meaning "to get up, rise to one's feet" (as in up and leave) is recorded from 1643. Sense of "to move upward" is recorded from 1737. Meaning "increase" (as in up the price of oil) is attested from 1915. Cf. Old English verb uppian "to rise." Upping block is attested from 1796.
To raise; increase: My confidence has upped itself (1925+)
[first adjective sense is based on up, ''effervescent, bubbling,'' used of beer and other drinks; later similar uses, from the 1940s, are based on the ''high'' produced by narcotics]