congruence

Short definition from Wiktionary

Noun

1. 1
   The quality of agreeing or corresponding; being suitable and appropriate.
2. 2
   A relation between two numbers indicating they give the same remainder when divided by some given number.
3. 3
   The quality of being isometric — roughly, the same measure and shape.
4. 4
   Matrix similarity by an orthogonal matrix.
5. 5
   Any equivalence relation defined on an algebraic structure which is preserved by operations defined by the structure.