- Pacific Ocean
- palaeoclimate
- Palaeozoic
- Paleocene
- paleoecology
- paleontology
- palps
- pantropical
- paralectotype
- paraphyletic
- parapodium
- parasite
- parasitism
- part
- pectinate
- pedal
- pediform
- peduncles
- pelagic
- penial sucker
- penis
- Pennsylvanian
- penultimate
- peribuccal
- pericard
- periostracum
- phagocytosis
- pharynx
- phylogeny
- phytophage
- phytoplankton
- pigment
- pilose
- pl.
- planktivore
- plankton
- planorboid
- Pleistocene
- pleuston
- Pliocene
- plumose
- polar
- polyphyletic
- population
- posterior
- posterior footlobe
- postlarval
- predator
- primary production
- proboscis
- prodissoconch
- protoconch I
- protrandry
- protuberance
- proximal
- pseudoconch
- pyriform