The Collaborative International Dictionary of English v.0.48:

Renege \Re*nege"\ (r?-n?j" or r?-n?g"), v. t. [LL. renegare. See
   Renegade.]
   To deny; to disown. [Obs.] --Shak.
   [1913 Webster]

         All Europe high (all sorts of rights reneged)
         Against the truth and thee unholy leagued. --Sylvester.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Renege \Re*nege"\, v. i.
   1. To deny. [Obs.] --Shak.
      [1913 Webster]

   2. To fail to keep (a commitment or promise); -- often used
      with on; as, to renege on one's promise.
      [PJC]

   3. (Card Playing) To revoke; to play a card that cannot
      legally be played according to the rules. [R.]
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

renege
    n 1: the mistake of not following suit when able to do so [syn:
         revoke, renege]
    v 1: fail to fulfill a promise or obligation; "She backed out of
         her promise" [syn: renege, renege on, renegue on, go
         back on]