What is the meaning of Functor?

A function word.

A function object.

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.

A structure allowing a function to apply within a generic type, in a way that is conceptually similar to a functor in category theory.

functor (a mapping between categories)

functor

Source: wiktionary.org