Open English Wordnet
Nouns
Adjectives
(s)changeless, constant, invariant, unvaryingunvarying in nature“maintained a constant temperature”, “principles of unvarying validity”
(s)ceaseless, constant, incessant, never-ending, perpetual, unceasing, unremittinguninterrupted in time and indefinitely long continuing“the ceaseless thunder of surf”, “in constant pain”, “night and day we live with the incessant noise of the city”, “the never-ending search for happiness”, “the perpetual struggle to maintain standards in a democracy”, “man's unceasing warfare with drought and isolation”, “unremitting demands of hunger”