1540s, from un- (1) "not" + past participle of turn (v.).

"turned inward," 1843, from in (adv.) + past participle of turn (v.).

1868, "upturned part," from up (adv.) + turn (n.). Meaning "improvement" (especially in economics) is from 1930.

also turn-table, "circular platform designed to turn upon its center," 1835, originally in the railway sense, from turn (v.) + table (n.). The record-player sense is attested from 1908.

also turn-buckle, 1703, "catch or fastening for windows and shutters," from turn (v.) + buckle (n.). Meaning "coupling with internal screw threads for connecting metal rods" is attested from 1877.

"a decline," 1926 in an economic sense, from the prepositional phrase; see down (adv.) + turn (n.).

1590s, "turning in of the toes" (especially in dancing), from in + turn. In wrestling, "a lifting with the thigh" (c. 1600).

1650s, "jailer," from turn (v.) + key (n.). In reference to a job that only has to be done only once, it is recorded from 1934. The notion probably is of something that can be accomplished with a single turn of a key.

1550s, from turn (v.) + coat (n.). The image is of one who attempts to hide the badge of his party or leader. The expression to turn one's coat "change principles or party" is recorded from 1570s.

also turn-over, 1650s, "action of turning over," from the verbal phrase; see turn (v.) + over (adv.). As a kind of pastry tart, from 1798. Meaning "number of employees leaving a place and being replaced" is recorded from 1955.