1. Suppressing or eliminating engine knock in combustion engines
   - antiknock

See also: leaded

• genus Piroplasma
• genus Pisanosaurus
• genus Piscidia
• genus Pisonia
• genus Pistacia
• genus Pistia
• genus Pisum
• genus Pithecanthropus
• genus Pithecellobium
• genus Pithecia
• genus Pithecolobium
• genus Pitta
• genus Pituophis
• genus Pitymys
• genus Pityrogramma
• genus Placuna
• genus Plagianthus
• genus Planera
• genus Planococcus
• genus Plantago
• genus Plasmodiophora
• genus Plasmodium
• genus Platalea
• genus Platanthera
• genus Platanus