Definition of "arity" [arity]

• The number of arguments or operands a function or operation takes. For a relation, the number of domains in the corresponding Cartesian product. (noun)

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• "r is called the arity of the function f, i.e., the number of arguments that it takes."
• "Then due to its popul­arity, the dates were extended twice until the end of August."
• "A structure contains interpretations of certain predicate, function and constant symbols; each predicate or function symbol has a fixed arity."