arity

(logic, mathematics, computer science) The number of arguments or operands a function or operation takes. For a relation, the number of domains in the corresponding Cartesian product.

(mathematics, computer science) The maximum number of child nodes that any node in a given tree (data structure) may have.

(Lojban grammar) the number of arguments (in Lojban grammar called sumti) specified in the definition of a selbri. (the selbri combined with the sumti make up a bridi).