Noun
a closed chain of 6 carbon atoms with hydrogen atoms attached
Source: WordNetIt has: * A rigid pentacyclic structure consisting of a benzene ring (A), two partially unsaturated cyclohexane rings (B and C), a piperidine ring (D) and a tetrahydrofuran ring (E). Source: Internet
This is seen in, for example, phenol (C 6 H 5 –OH), which is acidic at the hydroxyl (OH), since a charge on this oxygen (alkoxide –O − ) is partially delocalized into the benzene ring. Source: Internet