The Collaborative International Dictionary of English v.0.48:

Carp \Carp\ (k[aum]rp), v. i. [imp. & p. p. Carped
   (k[aum]rpt); p. pr. & vb. n. Carping.] [OE. carpen to say,
   speak; from Scand. (cf. Icel. karpa to boast), but influenced
   later by L. carpere to pluck, calumniate.]
   1. To talk; to speak; to prattle. [Obs.] --Chaucer.
      [1913 Webster]

   2. To find fault; to cavil; to censure words or actions
      without reason or ill-naturedly; -- usually followed by
      at.
      [1913 Webster]

            Carping and caviling at faults of manner. --Blackw.
                                                  Mag.
      [1913 Webster]

            And at my actions carp or catch.      --Herbert.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Carping \Carp"ing\ (k[aum]rp"[i^]ng), a.
   Fault-finding; censorious caviling. See Captious. --
   Carp"ing*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

carping
    n 1: persistent petty and unjustified criticism [syn:
         faultfinding, carping]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "carping":
   adverse criticism, animadversion, aspersion, bad notices,
   bad press, blameful, captious, captiousness, cavil, caviling,
   censorious, censoriousness, condemnatory, critical, criticism,
   cynical, damnatory, exception, faultfinding, flak, hairsplitting,
   hit, home thrust, hostile criticism, hypercritical,
   hypercriticalness, hypercriticism, imputation, jawing, knock,
   nagging, niggle, niggling, nit, nit-picking, objurgatory, obloquy,
   overcritical, overcriticalness, pestering, pettifogging,
   priggishness, quibble, quibbling, railing, rap, reflection,
   reproachful, reproachfulness, slam, stricture, swipe,
   taking exception, trichoschistic, trichoschistism, ultracritical,
   upbraiding