(category theory) A category 𝒞 with a bifunctor ⊗:𝒞×𝒞→𝒞 which may be called tensor product, an associativity isomorphism α_(A,B,C):(A⊗B)⊗C≃A⊗(B⊗C), an object I which may be called tensor unit, a left unit natural isomorphism λ_A:I⊗A≃A, a right unit natural isomorphism ρ_A:A⊗I≃A, and some "coherence conditions" (pentagon and triangle commutative diagrams for those isomorphisms).

In mathematics, especially in category theory, a closed monoidal category (or a monoidal closed category) is a category that is both a monoidal category and a closed category in such a way that the structures are compatible.

In category theory, a branch of mathematics, a symmetric monoidal category is a monoidal category (i.e. a category in which a "tensor product" is defined) such that the tensor product is symmetric (i.e. is, in a certain strict sense, naturally isomorphic to for all objects and of the category).

In category theory, monoidal functors are functors between monoidal categories which preserve the monoidal structure.