In IUPAC nomenclature, a parent structure, parent compound, parent name or simply parent is the denotation for a compound consisting of an unbranched chain of skeletal atoms (not necessarily carbon), or consisting of an unsubstituted monocyclic or polycyclic ring system. Parent structures bearing one or more functional groups that are not specifically denoted by a suffix are called functional parents. Names of parent structures are used in IUPAC nomenclature as basis for systematic names.