late 14c., permuten, "to change one for another, to interchange," from Old French permuter and directly from Latin permutare "to change thoroughly," from per "thoroughly" (see per) + mutare "to change" (from PIE root *mei- (1) "to change, go, move"). The mathematical sense is from 1878 (see permutation).
permission
permissive
permit
permutate
permutation
permute
pern
pernicious
pernickety
perorate
peroration