Old English stelan "to commit a theft" (class IV strong verb; past tense stæl, past participle stolen), from Proto-Germanic *stelanan (cf. Old Saxon stelan, Old Norse, Old Frisian stela, Dutch stelen, Old High German stelan, German stehlen, Gothic stilan), of unknown origin.
Most IE words for steal have roots in notions of "hide," "carry off," or "collect, heap up." Attested as a verb of stealthy motion from c.1300 (e.g. to steal away, late 14c.); of glances, sighs, etc., from 1580s. To steal (someone) blind first recorded 1974.
"a bargain," by 1942, American English colloquial, from steal (v.). Baseball sense of "a stolen base" is from 1867.
The diversion of blood flow from its normal course.
One's constant and only boyfriend or girlfriend (1897+)