Source : Webster's Revised Unabridged Dictionary (1913)

Hydrolysis \Hy*drol"y*sis\, n. [Hydro-, 1 + -lysis.] (Chem.)
   A chemical process involving the addition of the elements of
   water.

Source : WordNet®

hydrolysis
     n : a chemical reaction in which water reacts with a compound to
         produce other compounds; involves the splitting of a bond
         and the addition of the hydrogen cation and the hydroxide
         anion from the water