Periodicity or periodic may refer to:

• Bott periodicity theorem, addresses Bott periodicity: a modulo-8 recurrence relation in the homotopy groups of classical groups
• Periodic function, a function whose output contains values that repeat periodically
• Periodic mapping

• Periodic table of chemical elements
• Periodic trends, relative characteristics of chemical elements observed
• Redshift periodicity, astronomical term for redshift quantization

• Fokker periodicity blocks, which mathematically relate musical intervals
• Periodic acid, a compound of iodine
• Principle of periodicity, a concept in generally accepted accounting principles
• Quasiperiodicity, property of a system that displays irregular periodicity

• Aperiodic (disambiguation)
• Cycle (disambiguation)
• Frequency (disambiguation)
• Period (disambiguation)
• Periodical
• Seasonality, periodic variation, or periodic fluctuations