Wiktionary
multicategory
n. (context mathematics English) A generalization of the concept of category that allows morphisms of multiple arity
Wikipedia
Multicategory
In mathematics (especially category theory), a multicategory is a generalization of the concept of category that allows morphisms of multiple arity. If morphisms in a category are viewed as analogous to functions, then morphisms in a multicategory are analogous to functions of several variables.