cap·sa·i·cin (k²p-s³"¹-s¹n) n. A colorless, pungent, crystalline compound, C18H27NO3, that is derived from capsicum and is a strong irritant to skin and mucous membranes. [capsic(um) (perhaps influenced by Latin capsa, box; see CAPSICUM) + -in.]

cap·si·cum (k²p"s¹-k…m) n. 1. Any of various tropical American pepper plants of the genus Capsicum, especially any of the numerous cultivated forms of the species C. annuum and C. frutescens. 2. The fruit of any of these plants, especially the dried pungent types used as a condiment and in medicine. [New Latin Capsicum, genus name, perhaps from Latin capsa, box (from its podlike fruit).]