In taxonomy, this refers to 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, and so is "bare" or "naked" name.

Since a nomen nudum fails to qualify as a formal scientific name, a later author may publish a valid scientific name which is identical in spelling. If the same author publishes a name first as a nomen nudum and then later if it is accompanied by a valid description, the date of publication of the last valid description will become the taxon's date of establishment.