A nomen illegitimum is a technical term, used mainly in botany

Botany

Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

. It is usually abbreviated as nom. illeg..

Definition

This term refers to a validly published name, but one that contravenes some of the articles laid down by the International Botanical Congress

International Botanical Congress

International Botanical Congress is a large-scale meeting of botanists in all scientific fields, from all over the world. Authorized by the International Association of Botanical and Mycological Societies , congresses are held every six years with the venue circulating around the world. The XVIII...

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A nomen illegitimum could be a validly published name that must be rejected for the purposes of priority in accordance with the International Code of Botanical Nomenclature. The name could be superfluous at its time of publication either because the taxon (as represented by the type specimen) already has a name (a superfluous name), or because the name has already been applied to another plant (a homonym).

See also

• Correct name (botany)
  Correct name (botany)
  In botany, the correct name according to the International Code of Botanical Nomenclature is the one and only botanical name that is to be used for a particular taxon, when that taxon has a particular circumscription, position and rank. Determining whether a name is correct is a complex procedure...
  
  
• Valid name (zoology)
  Valid name (zoology)
  In zoological nomenclature, the valid name of a taxon is the zoological name that is to be used for that taxon following the rules in the International Code of Zoological Nomenclature . In other words: a valid name is the correct zoological name of a taxon.In contrast, an invalid name is a name...
  
  
• Nomen dubium
  Nomen dubium
  In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
  
  
• Glossary of botanical terms
  Glossary of botanical terms
  Many of the terms used in Wikipedia glossaries are already defined and explained within Wikipedia itself. However, lists like the following indicate where new articles need to be written and are also useful for looking up and comparing large numbers of terms together.This glossary is incomplete;...
  
  
• Nomen conservandum