changeless

adjectives

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"

changeless, immutable

is derived from

unvarying in nature

"maintained a constant temperature"; "principles of unvarying validity"

changeless, constant, invariant, unvarying

is derived from

remaining the same for indefinitely long times

changeless, unalterable

is derived from