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.
- (article 52) it was superfluous at its time of publication, i.e., the taxon (as represented by the type) already has a name, or
- (articles 53 and 54) the name has already been applied to another plant (a homonym).
For the procedure of rejecting otherwise legitimate names, see conserved name.
- "The generic name Cainito Adans. (1763) is illegitimate because it was a superfluous name for Chrysophyllum L. (1753), which Adanson cited as a synonym."
- "The name Amblyanthera Müll. Arg. (1860) is a later homonym of the validly published Amblyanthera Blume (1849) and is therefore unavailable for use, although Amblyanthera Blume is now considered to be a synonym of Osbeckia L. (1753)."
- "The name Torreya Arn. (1838) is a nomen conservandum and is therefore available for use in spite of the existence of the earlier homonym Torreya Raf. (1818)."
- Correct name (botany)
- Valid name (zoology)
- Nomen dubium
- Glossary of botanical terms
- Glossary of scientific naming
- Nomen conservandum