Old English styrian, from Proto-Germanic *sturjanan (cf. Middle Dutch stoeren, Dutch storen "to disturb," Old High German storan "to scatter, destroy," German stören "to disturb"), probably from the root of storm (q.v.). The noun sense of "commotion, disturbance, tumult" (late 14c., in phrase on steir) is probably from Old Norse styrr "disturbance, tumult" (see storm), from the same Proto-Germanic root; the sense of "movement, bustle" is probably from the English verb. Stir-fry (v.) is attested from 1959.
Despicable; nasty; stinking (1940s+)