Period and periodic may refer to:

• Full stop, also known as a period, that marks the end of a sentence
• Menstrual cycle, relating to the reproductive system
• Period (music)
• Period (rhetoric)
• Historical period

Science

• Orbital period, in astronomy
• Periodic function, in mathematics
• Periodic table, in chemistry
• Periodic table period, in chemistry
• Periodic acid, in chemistry
• Geologic period, in geology

Mathematics

• Periodic function
• Recurring decimal
• In a group, the period of an element a is the smallest integer n such that aⁿ = e, the identity.
• In physics, a period is an interval of time between the recurrence of phases in a vibration, etc. This general sense applies to many of the above.
• Period (Business) the word 'Period' on a pay slip states how much money has been taxed from that "period" or session of pay (Normally the month).

Period is also the name of the final novel in Dennis Cooper's George Miles Cycle.

Perioda | Periode | Περίοδος | Período | Periodo | Période | Período | 주기 | Periodo | Periode | ピリオド | Okres (strona ujednoznaczniająca) | Período | Период | Perióda | Nihajni čas | Jakso | Period | Chu kỳ