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Period (from Greek περίοδος) or periodic may refer to:

  • Era, a length or span of time
  • Full stop or period, a punctuation mark


  • Wave period, the time taken for one full oscillation
  • Orbital period, the time for one object to complete an orbit around another
  • Period (periodic table), a horizontal row of the periodic table
  • Menstruation, is sometimes referred to as a "period" as it is the periodic discharge of blood and mucosal tissue (the endometrium) from the uterus and vagina
  • Period (gene), a gene in Drosophila involved in regulating circadian rhythm
  • Period (geology), a subdivision of geologic time


  • Periods (ring), members of the ring of numbers that can be expressed as integrals of algebraic differential forms over algebraically defined domains
  • Periodic point, a point that is visited by a dynamic system with a certain period (frequency)


  • Period piece, a creative work set in a particular era
  • Period (music), a concept in musical composition
  • Period, the final book in Dennis Cooper's George Miles cycle of novels
  • Period furniture, period clothing, etc., usually referring to antique items, or copies of antiques; used in furnishing an old building or in a stage or film production, to lend authenticity to the setting by reflecting the specific era of the architecture or the story



See also