In IUPAC nomenclature

IUPAC nomenclature

A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry ....

, 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

Cyclic compound

In chemistry, a cyclic compound is a compound in which a series of atoms is connected to form a loop or ring.While the vast majority of cyclic compounds are organic, a few inorganic substances form cyclic compounds as well, including sulfur, silanes, phosphanes, phosphoric acid, and triboric acid. ...

 or polycyclic ring system.

Parent structures bearing one or more functional group

Functional group

In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...

s 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.

A parent hydride

Parent hydride

In IUPAC nomenclature, a parent hydride is an unbranched acyclic or cyclic structure to which only hydrogen atoms are attached. Parent hydrides are parent structures that contain one or more hydrogen atoms...

 is a parent structure with one or more hydrogen atoms. Parent hydrides have a defined standard population of hydrogen atoms attached to a skeletal structure. Parent hydrides are used extensively in organic nomenclature, but are also used in inorganic chemistry.
To construct a systematic name

Systematic name

A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection...

, affix

Affix

An affix is a morpheme that is attached to a word stem to form a new word. Affixes may be derivational, like English -ness and pre-, or inflectional, like English plural -s and past tense -ed. They are bound morphemes by definition; prefixes and suffixes may be separable affixes...

es are attached to the parent name, which denote substituents that replace hydrogen.