promethazine

noun

pro·meth·a·zine | \ (ˈ)prō-ˈmeth-ə-ˌzēn

Medical Definition of promethazine

: a crystalline antihistamine drug derived from phenothiazine and used chiefly in the form of its hydrochloride C₁₇H₂₀N₂S·HCl — see phenergan