A cavity refers to the hollow of a body. It may refer to:

  • Cavity or Dental caries, damage to the structure of teeth
  • Body cavity, a fluid filled space in many animals where organs typically develop
  • Cavity wall, a wall consisting of two skins with a cavity.
  • Resonator, a device designed to select for waves of particular wavelengths
    • Optical cavity, the cavity resonator of a laser
    • Microwave cavity or RF cavity, a cavity resonator in the Radio Frequency range, for example used in particle accelerators
  • Cavitation, the phenomenon of partial vacuums forming in fluid, for example, in propellors
  • Cavitary pneumonia, a type of pneumonia in which a hole is formed in the lung
  • Cavity (band), a sludge metal band from Miami, Florida.