commutation
com.mu.ta.tion \.ka:m-y*-'ta--sh*n\ n [ME, fr. MF, fr. L commutation-, commutatio, fr. commutatus,]pp. of commutare 1: EXCHANGE, TRADE 2: REPLACEMENT; specif : a substitution of one form of paymen t or charge for another 3: a change of a legal penalty or punishment to a lesser one 4: an act of commuting 5: the action of commutating