Cyclic compounds having as ring members atoms of at least two different elements,
e.g. quinoline, 1,2-thiazole, bicyclo[3.3.1]tetrasiloxane.
Source:
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on
structure (IUPAC Recommendations 1995))
on page 1340