Describing a compound that has a ring of atoms in its molecules. In homocyclic compounds all the atoms in the ring are the same type, e.g. benzene (C6H6) and cyclohexane (C6H12). These two examples are also examples of carbocyclic compounds; i.e. the rings are of carbon atoms. If different atoms occur in the ring, as in pyridine (C5H5N), the compound is said to be heterocyclic.