Source : Webster's Revised Unabridged Dictionary (1913)

Permutable \Per*mut"a*ble\, a. [Cf. F. permutable.]
   Capable of being permuted; exchangeable. --
   {Per*mut"a*ble*ness}, n. -- {Per*mut"a*bly}, adv.

Source : WordNet®

permutableness
     n : ability to change sequence [syn: {permutability}, {transposability}]