Nor-

In chemical nomenclature, nor- is a prefix to name a structural analog that can be derived from a parent compound by the removal of one carbon atom along with the accompanying hydrogen atoms. The nor-compound can be derived by removal of a , , or CH group, or of a C atom. The "nor-" prefix also includes the elimination of a methylene bridge in a cyclic parent compound, followed by ring contraction. (The prefix "homo-" which indicates the next higher member in a homologous series, is usually limited to noncyclic carbons). The terms desmethyl- or demethyl- are synonyms of "nor-".