In taxonomy, a nomen nudum ('naked name'; plural nomina nuda) is a designation[1] which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published with an adequate description. This makes it a "bare" or "naked" name, which cannot be accepted as it stands.[2] A largely equivalent but much less frequently used term is nomen tantum ("name only"). Sometimes, "nomina nuda" is erroneously considered a synonym for the term "unavailable names". However, not all unavailable names are nomina nuda.[3]
According to the rules of zoological nomenclature a nomen nudum is unavailable; the glossary of the International Code of Zoological Nomenclature gives this definition:[4]
And among the rules of that same Zoological Code:
According to the rules of botanical nomenclature a nomen nudum is not validly published. The glossary of the International Code of Nomenclature for algae, fungi, and plants gives this definition:[5] The requirements for the diagnosis or description are covered by articles 32, 36, 41, 42, and 44.[5]
From 1 January 1935 to 31 December 2011, to be validly published it was also required that the description or diagnosis be in Latin as reaffirmed in the Melbourne Code article 39. After 2011 it was only recommended that the authors include or cite a Latin or English description or diagnosis.
Nomina nuda that were published before 1 January 1959 can be used to establish a cultivar name. For example, Veronica sutherlandii, a nomen nudum, has been used as the basis for Hebe pinguifolia 'Sutherlandii'.[6]