The benzene nucleus refers to a six-carbon ring structure in which each carbon is bonded to two neighboring carbons and one hydrogen atom. Synonyms for benzene nucleus include phenyl ring, benzene ring, and aryl ring. These terms are often used interchangeably to refer to the same structure. The term "phenyl" is often used to indicate a specific functional group in which the benzene ring is attached to another molecule. The term "aryl" is a more general term used to describe any aromatic ring system. Regardless of terminology, the benzene nucleus plays an important role in organic chemistry and is a common feature in many natural and synthetic compounds.