From the Merriam-Webster online dictionary:
Etymology: Middle English, from Old Norse beit pasturage & beita food; akin to Old English bItan to bite
1 a : something (as food) used in luring especially to a hook or trap b : a poisonous material placed where it will be eaten by harmful or objectionable animals
2 : LURE, TEMPTATION
From The Devil's Dictionary by Ambrose Bierce:
A preparation that renders the hook more palatable. The best kind is beauty.