nonperiodic Antonyms

annual nightly oscillatory periodic periodical quarterly semimonthly semiweekly tertian triennial yearly biannual biyearly semiannual midweekly semestral monthly menstrual hourly biennial bimestrial bimonthly biweekly catamenial centennial cyclic daily decennial diurnal fortnightly half-hourly half-yearly hebdomadal hebdomadary semestrial