- any of a group of internal esters derived from hydroxy acids.
- any of a class of organic compounds formed from hydroxy acids and containing the group -C(CO)OC-, where the carbon atoms are part of a ring
- An anhydride formed by the removal of a water molecule from the hydroxyl and carboxyl radicals of hydroxy acids.
- Any of various organic esters derived from organic acids by removal of water. Lactones are formed when the carboxyl (COOH) group of the acid reacts with a hydroxyl (OH) group in the same acid, releasing water and causing the carbon atom to join to the hydroxyl’s remaining oxygen atom, forming a ring. Vitamin C, the antibiotic erythromycin, and many commercially important substances are lactones.