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Definition of permutation:
 Any one of such possible arrangements.
 Barter; exchange.
 The act of permuting; exchange of the thing for another; mutual transference; interchange.
 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.
Synonyms:
switching, commutation, switch, replenishment, reversal, transformation, concoction, combination, alteration, alternate, variation, electrical switch, replacing, mixture, heterotaxy, modification, refilling, transposition, jumble, electric switch, amalgam, exchange, compound, shift, mutation, surrogate, replacement, substitute, mix, successor, combo, renewal, blend, hybrid, change, substitution.
Usage examples:

He says that every possible permutation of the four bells must be rung once, and once only.
 "Amusements in Mathematics", Henry Ernest Dudeney. 
I was, however, perfectly fascinated with the mathematical rules of " combination, permutation, and variation," but unhappily I could not give much time to their study, which I have regretted ever since.
 "Autobiography of Friedrich Froebel", Friedrich Froebel. 
When you have what seems a good situation, don't rush into another at your earliest opportunity, but instead study it till you know every permutation and combination it holds emotionally for every one involved, both because the situation affects every character, and because every character may affect all the others.
 "Dramatic Technique", George Pierce Baker.