Source : Webster's Revised Unabridged Dictionary (1913)

Saponify \Sa*pon"i*fy\, v. t. [imp. & p. p. {Saponified}; p. pr.
   & vb. n. {Saponifying}.] [L. sapo, -onis, soap + -fy: cf. F.
   saponifier.]
   To convert into soap, as tallow or any fat; hence (Chem.), to
   subject to any similar process, as that which ethereal salts
   undergo in decomposition; as, to saponify ethyl acetate.

Source : WordNet®

saponify
     v 1: become converted into soap by being hydrolized into an acid
          and alcohol as a result of being treated with an alkali;
          "the oil saponified"
     2: convert into soap by hydrolizing an ester into an acid and
        alcohol as a result of treating it with an alkali;
        "saponify oils and fats"
     [also: {saponified}]