hy·drol·y·sis \hīdräləsə̇s\noun Etymology: International Scientific Vocabulary hydr- + -lysis : a chemical reaction of water in which a bond in the reactant other than water is split and hydrogen and hydroxyl are added with the formation usually of two or more new compounds, some types of hydration however often being included < hydrolysis of a salt to an acid and a base > < hydrolysis of an ester to an acid and an alcohol > — compare saponification, solvolysis