noun A category homomorphism; a morphism from a source category to a target category which maps objects to objects and arrows to arrows (either covariantly or contravariantly), in such a way as to preserve morphism composition and identities.
In the category of categories ๐๐๐ญ the objects are categories and the morphisms are functors.
noun A structure allowing a function to apply within a generic type, in a way that is conceptually similar to a functor in category theory.