What do a.m. and p.m. stand for?


[pur-myoo-tey-shuh n] /ˌpɜr myʊˈteɪ ʃən/
the act of permuting or permutating; alteration; transformation.
  1. the act of changing the order of elements arranged in a particular order, as abc into acb, bac, etc., or of arranging a number of elements in groups made up of equal numbers of the elements in different orders, as a and b in ab and ba; a one-to-one transformation of a set with a finite number of elements.
  2. any of the resulting arrangements or groups.
    Compare combination (def 8b).
Origin of permutation
1325-75; Middle English permutacioun (< Middle French permutacion) < Latin permūtātiōn- (stem of permūtātiō) thoroughgoing change. See per-, mutation, permute
Related forms
permutational, adjective
permutationist, noun
1. modification, transmutation, change. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for permutation
  • Right now, moviegoers are riding a wave of movies that feature insects in every possible permutation.
  • The interesting permutation in this backchannel backlash, to me, is that it was conducted silently.
  • The reason is that every possible permutation needs to be looked at in order to find the best.
  • Each is a permutation of the other, with no two alike.
  • Add light, in any permutation of color, saturation and brightness.
  • The officers have seen almost every permutation of sin.
  • There is no permutation of political correctness that does not have some celebrity's name attached to it.
  • Especially since each can project their own permutation of policy into that empty vessel, but even so.
  • As in any system, the logic goes, the higher the number of permutation the higher the likely hood of success.
  • Another permutation on these suggestions: call your mortgage company and tell them you're ready to quit-claim and walk away.
British Dictionary definitions for permutation


  1. an ordered arrangement of the numbers, terms, etc, of a set into specified groups: the permutations of a, b, and c, taken two at a time, are ab, ba, ac, ca, bc, cb
  2. a group formed in this way. The number of permutations of n objects taken r at a time is n!/(nr)! nPr Compare combination (sense 6)
a combination of items made by reordering
an alteration; transformation
a fixed combination for selections of results on football pools Usually shortened to perm
Derived Forms
permutational, adjective
Word Origin
C14: from Latin permūtātiō, from permūtāre to change thoroughly; see mutation
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for permutation

mid-14c., from Old French permutacion "change, shift" (14c.), from Latin permutationem (nominative permutatio) "a change, alteration, revolution," noun of action from past participle stem of permutare "change thoroughly, exchange," from per- "thoroughly" (see per) + mutare "to change" (see mutable).

Online Etymology Dictionary, © 2010 Douglas Harper
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permutation in Technology

1. An ordering of a certain number of elements of a given set.
For instance, the permutations of (1,2,3) are (1,2,3) (2,3,1) (3,1,2) (3,2,1) (1,3,2) (2,1,3).
Permutations form one of the canonical examples of a "group" - they can be composed and you can find an inverse permutation that reverses the action of any given permutation.
The number of permutations of r things taken from a set of n is
n P r = n! / (n-r)!
where "n P r" is usually written with n and r as subscripts and n! is the factorial of n.
What the football pools call a "permutation" is not a permutation but a combination - the order does not matter.
2. A bijection for which the domain and range are the same set and so
f(f'(x)) = f'(f(x)) = x.

The Free On-line Dictionary of Computing, © Denis Howe 2010
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