"food put on a hook or trap to lure prey," c.1300, from O.N. beita "food," related to O.N. beit "pasture," O.E. bat "food," lit. "to cause to bite" (see bait (v.)). Figurative sense "anything used as a lure" is from c.1400. The verb in this sense, "to put food on a hook or in a trap," is attested from c.1300, probably from the noun.
"to torment or goad (someone unable to escape, and to take pleasure in it)," c.1200, beyten, a figurative use from the literal sense of "to set dogs on," from the medieval entertainment of setting dogs on some ferocious animal to bite and worry it (the literal use is attested from c.1300); from O.N. beita "to cause to bite," from P.Gmc. *baitan (cf. O.E. bętan "to cause to bite," O.H.G. beizzen "to bait," M.H.G. beiz "hunting," Ger. beizen "to hawk, to cauterize, etch"), causative of *bitan (see bite); the causative word forked into the two meanings of "harass" and "food offered."