The etymology surprised me. I didn't copy all the definitions.
Abet
(A*bet") v. t. [imp. & p. p. Abetted ; p. pr. & vb. n. Abetting.] [OF. abeter; a (L. ad) + beter to bait fr. Icel. beita to set dogs on, to feed, originally, to cause to bite, fr. Icel. bita to bite, hence to bait, to incite. See Bait, Bet.]

1. To instigate or encourage by aid or countenance; — used in a bad sense of persons and acts; as, to abet an ill-doer; to abet one in his wicked courses; to abet vice; to abet an insurrection. "The whole tribe abets the villany." South.