The Collaborative International Dictionary of English v.0.48:

Hypercritical \Hy`per*crit"ic*al\, a.
   1. Over critical; unreasonably or unjustly critical; carping;
      captious. "Hypercritical readers." --Swift.
      [1913 Webster]

   2. Excessively nice or exact. --Evelyn.
      [1913 Webster]

WordNet (r) 3.0 (2006):

hypercritical
    adj 1: inclined to judge too severely; "hypercritical of
           colloquial speech"; "the overcritical teacher can
           discourage originality" [syn: hypercritical,
           overcritical]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "hypercritical":
   captious, carping, caviling, censorious, critic, critical, cynical,
   faultfinding, hairsplitting, hypersensitive, morbidly sensitive,
   nagging, niggling, overconscientious, overcritical, overfastidious,
   overmeticulous, overnice, overparticular, overprecise, overrefined,
   overscrupulous, oversensitive, oversqueamish, pettifogging,
   quibbling, trichoschistic, ultracritical