late 14c., "thrust with a pointed weapon," first in Scottish English, apparently a dialectal variant of Scottish stob "to pierce, stab," from stob (n.), perhaps a variant of stub (n.) "stake, nail," but Barnhart finds this "doubtful." Figurative use, of emotions, etc., is from 1590s. Related: Stabbed; stabbing.

"wound produced by stabbing," mid-15c., from stab, v.. Meaning "act of stabbing" is from 1520s. Meaning "a try" first recorded 1895, American English. Stab in the back in the figurative sense "treacherous deed" is first attested 1881; the verbal phrase in the figurative sense is from 1888.