incommutable

/ˌɪnkəˈmjutəbəl/
adjective
  1. Not able to be changed, exchanged, or substituted.
    • Her loyalty to the cause was incommutable, unwavering through the years.
    • The terms of the treaty were incommutable, leaving no room for negotiation.
    • In mathematics, some operations are incommutable, meaning order matters.