/ ˌpɜːmjuˈteɪʃn; NAmE ˌpɜːrm-/ noun
[ usually pl. ] any of the different ways in which a set of things can be ordered :
The possible permutations of x, y and z are xyz, xzy, yxz, yzx, zxy and zyx.
••
WORD ORIGIN
late Middle English (in the sense exchange, barter ): via Old French from Latin permutatio(n-) , from the verb permutare change completely, from per- through, completely + mutare to change.