The Collaborative International Dictionary of English v.0.48:

Cavil \Cav"il\ (k[a^]v"[i^]l), v. i. [imp. & p. p. Caviled or
   Cavilled; p. pr. & vb. n. Caviling or Cavilling.] [L.
   cavillari to practice jesting, to censure, fr. cavilla
   bantering jests, sophistry: cf. OF. caviller.]
   To raise captious and frivolous objections; to find fault
   without good reason.
   [1913 Webster]

         You do not well in obstinacy
         To cavil in the course of this contract. --Shak.
   [1913 Webster]