Adjective
periodic -
happening or recurring at regular intervals; "the periodic appearance of the seventeen-year locust"
periodical
aperiodic ,
nonperiodic not recurring at regular intervals
cyclic recurring in cycles
oscillating ,
oscillatory having periodic vibrations
diurnal of or belonging to or active during the day; "diurnal animals are active during the day" ; "diurnal flowers are open during the day and closed at night" ; "diurnal and nocturnal offices"
day-after-day ,
day-by-day ,
day-to-day ,
daily of or belonging to or occurring every day; "daily routine" ; "a daily paper"
nightly happening every night; "nightly television now goes on until 3:00 or 4:00 a.m."
hebdomadal ,
hebdomadary ,
weekly of or occurring every seven days; "a weekly visit" ; "weekly paper"
semiweekly ,
biweekly occurring twice a week
hourly occurring every hour or payable by the hour; "hourly chimes" ; "hourly pay"
half-hourly occurring ever half hour
fortnightly ,
biweekly occurring every two weeks
yearly ,
annual completing its life cycle within a year; "a border of annual flowering plants"
biannual ,
half-yearly ,
semiannual ,
biyearly occurring or payable twice each year
biennial ,
biyearly having a life cycle lasting two seasons; "a biennial life cycle" ; "parsnips and carrots are biennial plants often grown as annuals"
triennial occurring every third year or lasting 3 years
monthly of or occurring or payable every month; "monthly payments" ; "the monthly newsletter"
bimestrial ,
bimonthly two months long; lasting two months
semimonthly ,
bimonthly occurring twice a month; "a semimonthly publication"
semestral ,
semestrial occurring every six months or during every period of six months
periodic -
recurring or reappearing from time to time; "periodic feelings of anxiety"
occasional
