incommutable
1. [ adjective ] not interchangeable or able to substitute one for another
Examples:

"a rare incommutable skill"

Related terms: unexchangeable
2. [ adjective ] (law) not subject to alteration or change
Related terms: commutable unalterable inconvertible
Similar spelling:   incomputable
  incommensurable
  incompatible
  incomparable
  incommutability
  incommensurate
  incontestable
  incommunicative
  incommode
  inconsolable
  incompatibility
  incompetent
  incompatibly
  incomparably
  incombustible