The Collaborative International Dictionary of English v.0.48:

Caviler \Cav"il*er\ or Caviller \Cav"il*ler\ (-[~e]r), n.
   One who cavils.
   [1913 Webster]

         Cavilers at the style of the Scriptures. --Boyle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

caviller
    n 1: a disputant who quibbles; someone who raises annoying petty
         objections [syn: quibbler, caviller, caviler,
         pettifogger]