Dirac may refer to:

  • Paul Dirac (1902–1984), Swiss-British theoretical physicist, Nobel laureate, and a founder of the field of quantum physics
  • Gabriel Andrew Dirac (1925–1984), graph theorist, Paul Dirac's stepson
In physics
  • Dirac bracket, a generalization of the Poisson bracket
  • Dirac constant, a reduced form of the Planck constant
  • Dirac delta function, a generalized mathematical function
  • Dirac equation, a relativistic quantum mechanical wave equation
  • Dirac notation, a standard notation for describing quantum states
  • Fermi–Dirac integral (disambiguation)
  • Fermi–Dirac statistics, used to describe energies of single particles that obey the Pauli exclusion principle
  • 5997 Dirac, a main-belt asteroid
  • Dirac (software), a relativistic quantum chemistry program
  • Dirac (video compression format), an open digital video codec developed by BBC Research
  • Dirac, Charente, a commune of the Charente département, in France
  • Dirac measure, a mathematical measure that is a probability measure