ceaseless, continual, continued, continuing, continuous, incessant, nonstop, perpetual, running, unbroken, unceasing, unremitting

dateless, deathless, endless, eternal, everlasting, immortal, interminable, permanent, undying, unendingchangeless, constant, stable, steady, unchanging, unvaryingdurable, enduring, lasting, persistentimperishable, indestructible

discontinuous, noncontinuous

intermittent, periodic, periodical, recurrent, recurringalternate, alternating, cyclic(or cyclical), rhythmic(or rhythmical), seasonal, serialerratic, fitful, irregular, occasional, spasmodic, sporadic, spotty, unsteady