An intramolecular organic anhydride formed from a hydroxyacid by the loss of water between a hydroxyl and a –COOH group; a cyclic ester.
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lac·ton·ic lak-'tän-ik adj
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lac·tone (lakґtōn) a cyclic organic compound in which the chain is closed by ester formation between a carboxyl and a hydroxyl group in the same molecule.Medical dictionary. 2011.