com·mu·ta·tive 
(kŏmyə-tā′tĭv, kə-mytə-tĭv)
(kŏmyə-tā′tĭv, kə-mytə-tĭv)adj.
1. Relating to, involving, or characterized by substitution, interchange, or exchange.
2. Independent of order. Used of a logical or mathematical operation that combines objects or sets of objects two at a time. If a × b = b × a, the operation indicated by × is commutative.
com·mu′ta·tivi·ty (kə-my′tə-tĭvĭ-tē) n.