changeless in WordNet English dictionary

1. not subject or susceptible to change or variation in form or quality or nature
   "the view of that time was that all species were immutable, created by God"
   immutable  changeless 
   
2. unvarying in nature
   "maintained a constant temperature"; "principles of unvarying validity"
   changeless  constant  invariant  unvarying 
   
3. remaining the same for indefinitely long times
   changeless  unalterable