The Collaborative International Dictionary of English v.0.48:

Congruity \Con*gru"i*ty\ (? or ?), n.; pl. Congruities. [Cf.
   F. congruit?.]
   1. The state or quality of being congruous; the relation or
      agreement between things; fitness; harmony;
      correspondence; consistency.
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            With what congruity doth the church of Rome deny
            that her enemies do at all appertain to the church
            of Christ?                            --Hooker.
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            A whole sentence may fail of its congruity by
            wanting one particle.                 --Sir P.
                                                  Sidney.
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   2. (Geom.) Coincidence, as that of lines or figures laid over
      one another.
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   3. (Scholastic Theol.) That, in an imperfectly good persons,
      which renders it suitable for God to bestow on him gifts
      of grace.
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