A fixed point of a correspondence; a point of a variety corresponding to itself under a correspondence.
A coincidence point.
Of objects, the property of being coincident; occurring at the same time or place.
Of events, the appearance of a meaningful connection when there is none.
More generally: any equivalence relation defined on an algebraic structure which is preserved by operations defined by the structure.
The quality of agreeing or corresponding; being suitable and appropriate.
Matrix similarity by an orthogonal matrix.
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.