Permutation

n.
  1. The act of permuting; exchange of the thing for another; mutual transference; interchange.
  2. (Math.) Barter; exchange.
    1. The arrangement of any determinate number of things, as units, objects, letters, etc., in all possible orders, one after the other; -- called also alternation. Cf. Combination, n., 4.
    2. Any one of such possible arrangements.
    Permutation lock ,
    a lock in which the parts can be transposed or shifted, so as to require different arrangements of the tumblers on different occasions of unlocking.