Source : Webster's Revised Unabridged Dictionary (1913)

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}.

Source : WordNet®

chloral hydrate
     n : a colorless crystalline drug used as a sedative; irritates
         the stomach and can be addictive