Synonyms for Periodic (same or very similar meaning)
WordNet sense 1 (recurring with measured regularity):
rhythmic, rhythmical
WordNet sense 2 (stopping and starting at regular intervals):
intermittent
WordNet sense 3 (marked by repeated cycles):
cyclic
WordNet sense 4 (happening or recurring at regular intervals):
periodical
WordNet sense 5 (recurring in scattered and irregular or unpredictable instances):
sporadic
From the ODE community, based on WordNet
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