Source : Webster's Revised Unabridged Dictionary (1913)

Anhydrous \An*hy"drous\, a. [Gr. ? wanting water; 'an priv. +
   "y`dwr water.]
   Destitute of water; as, anhydrous salts or acids.

Source : WordNet®

anhydrous
     adj : without water; especially without water of crystallization
           [ant: {hydrous}]