Nomen illegitimum

Nomen illegitimum (Latin for illegitimate name) is a technical term, used mainly in botany. It is usually abbreviated as nom. illeg. Although the International Code of Nomenclature for algae, fungi, and plants uses Latin terms for other kinds of name (e.g. nomen conservandum for "conserved name"), the glossary defines the English phrase "illegitimate name" rather than the Latin equivalent. However, the Latin abbreviation is widely used by botanists and mycologists.

A superfluous name is often an illegitimate name. Again, although the glossary defines the English phrase, the Latin equivalent nomen superfluum, abbreviated nom. superfl. is widely used by botanists.