adjective. Impossible to alter.

Not alterable; unchangeable; immutable.

adjective. incapable of changing or being altered

adjective. irrevocable or irreversible

adjective. of a sentence; that cannot be changed

adjective. not capable of being changed or altered

adjective. remaining the same for indefinitely long times

"No one form of Church polity as permanently unalterable is laid down in the New Testament though the apostolical order of bishops, or presbyters, and deacons, superintended by higher overseers (called bishops after the apostolic times), has the highest sanction of primitive usage."

alterable  

final  incommutable  incurable  last  unchangeable  

unalterably  

immovable  implacable  ineradicable  inflexible  instinctive  

adamant  adamantine  cast-iron  changeless  constant