adjective

• Relative to a period or periods.
• Having repeated cycles.
• Occurring at regular intervals.
• Periodical.
• (astronomy) Pertaining to the revolution of a celestial object in its orbit.
• (mathematics, stochastic processes, of a state) For which any return to it must occur in multiples of k time steps, for some k>1.
• (rhetoric) Having a structure characterized by periodic sentences.
• Relating to the highest oxidation state of iodine; of or derived from a periodic acid.