The Collaborative International Dictionary of English v.0.48:

Congruence \Con"gru*ence\, n. [L. congruentia: cf. OF.
   cornguence.]
   Suitableness of one thing to another; agreement; consistency.
   --Holland.
   [1913 Webster]

WordNet (r) 3.0 (2006):

congruence
    n 1: the quality of agreeing; being suitable and appropriate
         [syn: congruity, congruousness, congruence] [ant:
         incongruity, incongruousness]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "congruence":
   accord, accordance, affinity, agreement, assent, chorus,
   coequality, coherence, coincidence, compatibility, concert,
   concord, concordance, conformance, conformation, conformity,
   congeniality, congruency, congruity, consistency, consonance,
   consort, cooperation, correspondence, equality, equivalence,
   harmony, homogeneity, homoousia, identity, indistinguishability,
   intersection, no difference, oneness, overlap, parallelism, peace,
   rapport, sameness, self-consistency, self-identity, selfhood,
   selfness, selfsameness, symmetry, sync, synchronism, synonymity,
   synonymousness, synonymy, tally, timing, uniformity, union, unison,
   unisonance, unity