Synonyms For "Periodic" :
2 syllables:
cyclic, daily, monthly, nightly, weekly, yearly
3 syllables:
annual, bimonthly, biweekly, biyearly, diurnal, fortnightly, hourly, midweekly, semestral
4 syllables:
biannual, biennial, bimestrial, hebdomadal, occasional, oscillating, semestrial, semimonthly, semiweekly, triennial