recurring at intervals of time

periodic revivals of an interest in handicrafts.

occurring or appearing at regular intervals

periodic visits of a mail steamer to an island.

repeated at irregular intervals; intermittent

periodic outbreaks of the disease.

Physics . recurring at equal intervals of time.

Mathematics . (of a function) having a graph that repeats after a fixed interval (period) of the independent variable.

Astronomy .

characterized by a series of successive circuits or revolutions, as the motion of a planet or satellite.

of or pertaining to a period, as of the revolution of a heavenly body.

pertaining to or characterized by rhetorical periods, or periodic sentences.

adjective

constant , continual , irregular , lasting , permanent , sporadic , variable

adjective

alternate , annual , at various times , centennial , cyclic , cyclical , daily , epochal , every once in a while , every so often , fluctuating , hourly , infrequent , intermittent , isochronal , isochronous , monthly , occasional , on-again-off-again , on certain occasions , orbital , perennial , periodical , recurrent , recurring , regular , repeated , rhythmic , routine , seasonal , serial , spasmodic , sporadic , weekly , yearlynotes:periodic means happening or recurring at regular intervals; sporadic means occurring singly or occasionally or in scattered instances , fitful