The Collaborative International Dictionary of English v.0.48:

Congruent \Con"gru*ent\, a. [L. congruens, p. pr. of congruere:
   cf. F. congruent.]
   Possessing congruity; suitable; agreeing; corresponding.
   [1913 Webster]

         The congruent and harmonious fitting of parts in a
         sentence.                                --B. Jonson.
   [1913 Webster]

   Congruent figures (Geom.), concurring figures.
      [1913 Webster]

WordNet (r) 3.0 (2006):

congruent
    adj 1: corresponding in character or kind [syn: congruous,
           congruent] [ant: incongruous]
    2: coinciding when superimposed [ant: incongruent]

Moby Thesaurus II by Grady Ward, 1.0:

58 Moby Thesaurus words for "congruent":
   accordant, affirmative, agreeable, agreeing, answerable, at one,
   coequal, coexistent, coexisting, coextensive, coherent, coincident,
   coincidental, coinciding, commensurate, compatible, concordant,
   concurring, conformable, congenial, congruous, consentaneous,
   consentient, consistent, consonant, cooperating, cooperative,
   correspondent, corresponding, coterminous, en rapport, equal,
   equivalent, harmonious, in accord, in agreement, in rapport,
   in sync, in synchronization, inaccordance, inharmony, like-minded,
   of a piece, of like mind, of one mind, on all fours, positive,
   proportionate, reconcilable, self-consistent, symbiotic,
   synchronized, synchronous, synonymous, unanimous, uniform,
   unisonant, unisonous