• Pneumocystis jiroveci pneumonia, disease (formerly known as Pneumocystis carinii pneumonia)
• phencyclidine, a drug also known as Angel Dust
• Probabilistically checkable proof, a notion in the theory of computational complexity theory
• Partido Comunista del Peru, a.k.a. Shining Path
• Post correspondence problem, an important problem in computability theory
• pentachlorophenol, timber preservative
• Partido Comunista Português, Portuguese Communist Party
• priority ceiling protocol, a computer science concept