to turn (something) into (something else) probably retains the classical sense of "to shape on a lathe" (attested in Eng. from c.1300). To turn up "arrive" is recorded from 1755. Turning-point in the fig. sense is attested from 1836. Turn-off "something that dampens one's spirits" first recorded 1975 (said to have been in use since 1968); to turn (someone) on "excite, stimulate, arouse" is recorded from 1903. Someone should revive turn-sick "dizzy," which is attested from mid-15c. To turn (something) loose "set free" is recorded from 1590s. Turn around (v.) "reverse" is first attested 1880, Amer.Eng. Turn down (v.) "reject" first recorded 1891, Amer.Eng. Turn in "go to bed" is attested from 1690s, originally nautical. To turn the stomach "nauseate" is recorded from 1620s. To turn up one's nose as an expression of contempt is attested from 1779.
mid-13c., "action of rotation," from Anglo-Fr. tourn (O.Fr. tour), from L. tornus "turning lathe;" also partly a noun of action from turn
(v.). Meaning "an act of turning, a single revolution or part of a revolution" is attested from late 15c. Sense of "place of bending" (in
a road, river, etc.) is recorded from early 15c. Meaning "beginning of a period of time" is attested from 1853 (e.g. turn of the century, 1926). Sense of "act of good will" is recorded from c.1300. Meaning "spell of work" is from late 14c.; that of "an individual's time for action, when these go around in succession" is recorded from late 14c. Turn about "by turns, alternately" is recorded from 1640s. Phrase done to a turn (1780) suggests meat roasted on a spit. The turn of the screw (1796) is the additional twist to tighten its hold, sometimes with reference to torture by thumbscrews.