Fluctuation may refer to:

  • Quantum fluctuation arising from the uncertainty principle
    • Primordial fluctuations, density variations in the early universe
    • Universal conductance fluctuations, a quantum physics phenomenon encountered in electrical transport experiments in mesoscopic species
  • Statistical fluctuations, very important in statistics, statistical mechanics, and thermodynamics
    • Thermal fluctuations, statistical fluctuations in a thermodynamic variable
  • An alternative name for conjuncture, a critical combination of events in economics