Source : Webster's Revised Unabridged Dictionary (1913)

Paraldehyde \Par*al"de*hyde\, n. [Pref. para- + aldehyde.]
   (Chem.)
   A polymeric modification of aldehyde obtained as a white
   crystalline substance.

Source : WordNet®

paraldehyde
     n : a colorless liquid (a cyclic trimer of acetaldehyde) that is
         used as a sedative and a solvent [syn: {ethanal trimer}]