Chloral \Chlo"ral\, n. [Chlorine + alcohol.] 1. (Chem.) A colorless oily liquid, {CCl3.CHO}, of a pungent odor and harsh taste, obtained by the action of chlorine upon ordinary or ethyl alcohol. 2. (Med.) Chloral hydrate. {Chloral hydrate}, a white crystalline substance, obtained by treating chloral with water. It produces sleep when taken internally or hypodermically; -- called also {chloral}.