- Palaeozoic
- palate
- Palearctic
- Paleocene
- paleoecology
- paleontology
- pantropical
- paraphyletic
- parasite
- parasitism
- paratype
- parthenogenesis
- pathogen
- pectinate
- pediform
- peduncle
- pelage
- pelagic
- Pennsylvanian
- pentagon
- pericentric inversion
- phagocytosis
- pharynx
- phenetic taxonomy
- pheromones
- phoronids
- photo-identification
- phylogeny
- phytal
- phytophagous
- phytoplankton
- pigment
- pilose
- pinna
- pinocytosis
- placenta
- planktivore
- planktonic
- plant
- Pleistocene
- plesiomorphy
- Pliocene
- plumose
- pod
- poikilothermic
- polar
- pollen
- pollination
- polygyny
- polynya
- polyphyletic
- pond
- pool
- population
- porpoising
- post-anal hump
- post-canines
- posteriad
- posterior
- predator
- premaxilla
- premolar
- primary production
- proboscis
- process
- prodrome
- protoctist
- protrandry
- protuberance
- proximal
- punctate
- pup
- pupil