stir (v.)

Middle English stiren, from Old English styrian, stirian "to move, be or become active or busy, pass into motion," also transitive, "to agitate with a rotating motion (a liquid or mixture by hand or with an instrument), move, change the location of; rouse, agitate, incite, urge;" from Proto-Germanic *sturjan (source also of Middle Dutch stoeren, Dutch storen "to disturb," Old High German storan "to scatter, destroy," German stören "to disturb"), from PIE *(s)twer- (1) "to turn, whirl" (see storm (n.)). Related: Stirred; stirring.

By late 12c. as "be alive;" from early 14c. as "affect emotionally." To stir up is from mid-14c. in a literal sense; by 1540s as "rouse to action." Stir-fry is attested from 1959 in writings on Chinese cookery as a verb and noun.

late 14c., "commotion, disturbance, tumult," late 14c. (in phrase on steir), probably from a Scandinavian source, such as Old Norse styrr "disturbance, tumult," from the same root as stir (v.)). The sense of "state of movement, bustle, activity of many persons" (1560s) probably is from the English verb. For the meaning "lock-up, prison" in thieves' slang, see stir-crazy.