Formulas
- Hanbury Brown and Twiss effect
- History of centrifugal and centripetal forces
- KT (energy)
- Kac's lemma
- Kaluza–Klein theory
- Kazuhiko Nishijima
- Killing horizon
- Kinetic scheme
- Kinetic term
- Knudsen diffusion
- Kohn anomaly
- Kohn–Sham equations
- Kondo effect
- List of Italian inventions and discoveries
- Order and disorder