cyanide

cy·a·nide

noun \ˈsī-ə-ˌnīd, -nəd\

Definition of CYANIDE

: any of several compounds (as potassium cyanide) that contain the radical CN having a chemical valence of one, react with and inactivate respiratory enzymes, and are rapidly lethal producing drowsiness, tachycardia, coma, and finally death