Similar word to periodic:

cyclic, oscillatory, oscillating, diurnal, daily, day-to-day, day-by-day, day-after-day, nightly, weekly, hebdomadal, hebdomadary, semiweekly, biweekly, hourly, half-hourly, fortnightly, biweekly, annual, yearly, semiannual, biannual, biyearly, half-yearl