- pulmonary lobule
- pulmonary trunk
- pulmonary vein
- pulp cavity
- pulsating canal
- pulsating vacuole
- pulvinus, thenar
- punctate shell
- punctuated equilibrium
- pupil
- Purkinje cell layer, piriform neuron layer
- Purkinje cell, piriform neuron
- pustule
- pusule
- pycnaster
- pygostyle
- pyloric caecum
- pyloric gland
- pyloric region
- pylorus
- pyramid
- pyramid of biomass
- pyramid of energy
- pyramid of number
- pyramidal cell
- pyramidal layer
- pyriform apparatus (绦虫), pyriform organ(苔藓动物)
- pyriform gland
- pyriform lobe
- quadrat, sample plot
- quadrate bone
- quadratojugal bone
- quadrifora
- quadrilobulate lophophore
- quadrulus
- quarternary parasite
- quasisocial
- quincuncial
- r-extinction
- r-selection
- r-strategy
- race
- rachis
- radial canal
- radial corallite
- radial furrow
- radial line
- radial neuroglia cell, Müller's cell
- radial piece
- radial pin