1. Cyclic hemiacetals formed by intramolecular addition of a hydroxy group to an aldehydic or ketonic carbonyl group. They are thus 1-oxacy-cycloalkan-2-ols or unsaturated analogues, e.g.
  2. [obsolete] This term has also been used for hydroxy lactones, but such use is not recommended.
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1347 (