A name that does not fulfill the criteria set by the International Code of Zoological Nomenclature as a legally described scientific name and therefore cannot be used unless it is subsequently proposed correctly
A genus name is described as a nomen nudum if it has been insufficiently described or lacks a type species. For example, Arkansaurus, Coelurosaurus, and Likhoelesaurus are genera, each of which is described as nomen nudum.
A name that lacks a description.
The phrase nomen nudum is a Latin term, meaning "naked name". In taxonomy, this is used to indicate a term or phrase which looks like a scientific name, and may well have been intended to become a scientific name, but fails to be one because it was not published with an adequate description (or a reference to such a description), and thus is "bare" or "naked". As a nomen nudum fails to qualify as a formal scientific name a later author may publish a real scientific name that is identical in spelling.