Quat may refer to: Quat (surname), a Chinese surname Quaternary ammonium cation, a class of chemical molecules used as a disinfectant, surfactant, drug etc. Quaternion, a non-commutative extension of the complex numbers Quaternary (disambiguation), referring to four parts, divisions, or sets. Khat, an African plant whose leaves are chewed as a stimulant Phan Huy Quát, former prime minister of South Vietnam