Hydrolysis (greek: υδωρ [hydor] = “water” and λύσις [lýsis] = “solution”) is a chemical reaction in which a compound is cleaved by water. If a proton-donating compound (Brønsted acid) catalyzes the reaction, it is called “acid hydrolysis.” Formally one part of the cleaved reaction product receives a proton (H⁺), the other a hydroxyl (OH⁻) moiety of a water molecule. Hydrolysis can also be catalyzed by a base. The reverse reaction is called a “condensation reaction.”