Pronunciation: (ku-myOO'tu-tiv, kom'yu-tā"tiv),[key] —adj. 1. of or pertaining to commutation, exchange, substitution, or interchange.
2. Math. a. (of a binary operation) having the property that one term operating on a second is equal to the second operating on the first, as a × b = b × a. b. having reference to this property: commutative law for multiplication.