- Pyatnytska Church （Chernihiv）
- pycnidiophore
- pycnidiospore
- pycnidium
- pycniospore
- pycnium
- pycnocline
- pycnometer
- pycnometer, density bottle
- pycnonuclear reaction
- pycnosclerotium
- pycnosis
- pycnothyrium
- PYD
- pyelolithotomy
- pyelonephritis
- Pyemotidae
- PY equation
- pygaxis
- pygidium
- Pygmalion
- Pygmalion effect
- Pygmy dipole resonance
- pygmy dipole resonance
- pygmy galaxy