1. (

• immutable ,
• changeless ,

) 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" ;

2. (

• changeless ,
• constant ,
• invariant ,
• unvarying

) unvarying in nature; "maintained a constant temperature"; "principles of unvarying validity" ;

3. (

• changeless ,
• unalterable

) remaining the same for indefinitely long times ;