形容词mutable

1. 永远不变的;永恒的
    Something that is immutable will never change or cannot be changed.

    e.g. ...the eternal and immutable principles of right and wrong.
           永恒不变的对错法则

1. not subject or susceptible to change or variation in form or quality or nature

    e.g. the view of that time was that all species were immutable, created by God

    Synonym: changeless