permutation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The process of altering the order of a given set of objects in a group.
• noun The result of such a process; a rearrangement or recombination of elements.
• noun Mathematics A rearrangement of the elements of a set.
• noun A complete change; a transformation.

from The Century Dictionary.

• noun Interchange; concurrent changes; mutual change; change in general.
• noun Exchange; barter.
• noun In mathematics, a linear arrangement of objects resulting from a change of their order.
• noun In philology, the mutation or interchange of consonants, especially of allied consonants.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act of permuting; exchange of the thing for another; mutual transference; interchange.
• noun 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.
• noun Any one of such possible arrangements.
• noun (Law) Barter; exchange.
• noun 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun mathematics A one-to-one mapping from a finite set to itself.
• noun mathematics, combinatorics An ordering of a finite set of distinct elements.
• noun music A transformation of a set's prime form, by applying one or more of certain operations, specifically, transposition, inversion, and retrograde.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the act of changing the arrangement of a given number of elements
• noun act of changing the lineal order of objects in a group
• noun an event in which one thing is substituted for another
• noun complete change in character or condition