1. In logic and mathematics, a function or operation that maps elements from one set to another, or a word or morpheme that has a grammatical function rather than a concrete meaning.
Usage: technical; mathematics and logic
2. In category theory, a structure-preserving map between categories.
Usage: technical; advanced mathematics
3. In linguistics, a word or element that serves a grammatical purpose, such as a preposition or conjunction, rather than carrying primary semantic content.
Usage: technical; linguistics

Examples

• In mathematics, a functor is used to transform one algebraic structure into another while preserving key properties.
• The preposition 'in' is a functor that indicates spatial relationships.
• Category theory relies heavily on the concept of a functor to relate different mathematical structures.
• Functors in programming allow operations to be applied to different data types.
• The conjunction 'and' is a functor that connects two clauses or phrases.