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

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