sa·pon·i·fi·ca·tion 
(sə-pŏn′ə-fĭ-kāshən)
(sə-pŏn′ə-fĭ-kāshən)n.
A reaction in which an ester is heated with an alkali, such as sodium hydroxide, producing a free alcohol and a carboxylate salt, especially alkaline hydrolysis of a fat or oil to make soap.