benzene ring

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A hexagonal ring arrangement found in benzene and other aromatic compounds, consisting of six carbon atoms with alternating single and double bonds between them, and with each carbon atom bonded to a hydrogen atom, or to other atoms or groups of atoms in derivatives of benzene.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a closed chain of 6 carbon atoms with hydrogen atoms attached