- papilla
- papillate
- paraphyletic
- parapodial
- parapodium
- parasite
- parasitic
- paratomy
- parthenogenesis
- parthenogenetic
- pathogenic
- pectinate chaeta
- penial bulb
- penial chaeta
- penial sac
- penial sheath
- penis
- peptonephridium
- peristomial
- peristomium
- pharyngeal
- pharyngeal gland
- pharyngeal pad
- pharynx
- phylogenetical
- pilose
- plesioporous
- plexus
- Plumose
- polyphyletic
- polyploid
- porophore
- postatrial
- postclitellar
- posterior
- posteriorly
- preclitellar
- predatory
- proboscis
- prosopority
- prosoporous
- prostate
- prostatic
- prostatic pore
- prostomium
- protrusible
- protuberance
- proximal
- proximally
- pseudopenis