What is the meaning of Congruence?

The quality of agreeing or corresponding; being suitable and appropriate.

A relation between two numbers indicating they give the same remainder when divided by some given number.

The quality of being isometric — roughly, the same measure and shape.

Matrix similarity by an orthogonal matrix.

Any equivalence relation defined on an algebraic structure which is preserved by operations defined by the structure.

congruence

Source: wiktionary.org