something that brings one to alertness or out of sleep, 1965, often in the 1960s in reference to a shot of heroin in the morning. Phrase wake-up call is attested from 1968, originally a call one received from the hotel desk in the morning. Verbal phrase wake up is from 1530s; earlier the adverb was out (late 14c.)

"in difficulties," especially "short of money," 1821, slang; it was earlier a nautical expression, in reference to steering.

"act of dressing up in one's best clothes," 1865, from the verbal phrase (17c.); see dress (v.) + up (adv.).

1840, "right to the present time," from phrase up to date, probably originally from bookkeeping. As an adjective from 1865. Meaning "having the latest facts" is recorded from 1889; that of "having current styles and tastes" is from 1891.

1773, from up + river. As an adverb from 1848.

1767, "stand behind and support," from back (v.) + up (adv.). The meaning "move or force backward" is by 1834. Of water prevented from flowing, by 1837.

also buildup, 1927, "accumulation of positive publicity." Of any accumulation (but especially military) from 1943. The verbal phrase is attested from late 14c.; see build (v.) + up (adv.).

also mockup, "model, simulation" 1919, perhaps World War I, from the verbal phrase mock up "make an experimental model" (1911), from mock (v.) + up (adv.).

1905, originally in the argot of sales and business, from verbal phrase follow up "pursue closely, act on energetically" (1794); see follow (v.) + up (adv.).

also sunup, "sunrise," 1712, from sun (n.) + up (adv.). In local use in U.S., and, according to OED, also in Caribbean English and formerly in South Africa.