Dirac may refer to:
- People
- 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
- Other
- 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