Periodic

1. Relative to a period or periods.
2. Having repeated cycles.

Synonym: cyclic

3. Occurring at regular intervals.

Synonyms: cyclic

4. (astronomy) Pertaining to the revolution of a celestial object in its orbit.

Antonym: non-periodic

5. (mathematics, stochastic processes, of a state) For which any return to it must occur in multiples of k time steps, for some k>1.

Antonym: aperiodic

6. (rhetoric) Having a structure characterized by periodic sentences.