constantly
all the time, always, aye (Scot.) continually, continuously, endlessly, everlastingly, incessantly, interminably, invariably, morning, noon and night, night and day, nonstop, perpetually, persistently, relentlessly, (every) now and then, every so often, from time to time, intermittently, irregularly, now and again, occasionally, off and on, periodically, sometimes