early 14c. as a verbal phrase, "lift and take with the fingers," from pick (v.) + up (adv.). From 1510s as "take or get casually, obtain or procure as opportunity offers." Meaning "take (a person found or overtaken) into a vehicle or vessel," is from 1690s, also, of persons, "make acquaintance or take along" (especially for sexual purposes). Intransitive meaning "improve gradually, reacquire vigor or strength" is by 1741. Sense of "tidy up" is from 1861; that of "arrest" is from 1871; meaning "gain speed" is from 1922; meaning "to pay" (a check, tab, etc.) is from 1945. Pick-me-up "stimulating alcoholic drink" is attested from 1867.
1834, from adjectival phrase stay-at-home (1797); see stay (v.1).
early 15c., "voluntary," from Late Latin electivus, from elect-, past-participle stem of eligere "to pick out, choose" (see election). In U.S., in reference to school subjects studied at the student's choice, first recorded 1847. As a noun, from 1701.
1540s, "to spend time with unimportant matters, to work in a trifling way," a word of uncertain origin, apparently a frequentative form. Meaning "to pick at one's food" is from 1610s; that of "urinate" is from 1796 as a childish word. Related: Piddled; piddler; piddling.