Englishunchanging
adjective
the unchanging passivity of her face enraged him:
consistent, constant, regular, even, uniform, unvarying, predictable, stable, steady, fixed, permanent, perpetual, eternal;
sustained, lasting, persistent, uninterrupted, continuous, continual, ceaseless, incessant, unceasing, never-ending, non-stop, interminable, unabating, unabated, unrelieved, unremitting, relentless.
▷antonyms varying, changeable, inconsistent.
unchanging Oxford Dictionary of English