The Collaborative International Dictionary of English v.0.48:

Jib \Jib\, v. i. [Connected with jibe; cf. OF. giber to shake.]
   To move restively backward or sidewise, -- said of a horse;
   to balk. [Written also jibb.] [Eng.]
   [1913 Webster] Jib

The Collaborative International Dictionary of English v.0.48:

Jib \Jib\, v. t. & i. [imp. & p. p. Jibbed; p. pr. & vb. n.
   Jibbing.] Also Jibb \Jibb\ [Cf. Jib a sail, Gybe.]
   (Chiefly Naut.)
   To shift, or swing round, as a sail, boom, yard, etc., as in
   tacking.
   [Webster 1913 Suppl.]