Periodicity or periodic may refer to: Mathematics 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 Physical sciences Periodic table of chemical elements Periodic trends, relative characteristics of chemical elements observed Redshift periodicity, astronomical term for redshift quantization Other uses 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 See also Aperiodic (disambiguation) Cycle (disambiguation) Frequency (disambiguation) Period (disambiguation) Periodical Seasonality, periodic variation, or periodic fluctuations