The incorporation of one or more integral molecules of water into another species with or without displacement of one or more other atoms or groups. For example, the incorporation of water into the inner ligand sphere of an inorganic complex is an aquation reaction.
See also: hydration
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1086 (https://doi.org/10.1351/pac199466051077)