Nomen oblitum

A nomen oblitum (Latin for "forgotten name") is a technical term, used in zoology. In its present meaning it came into being with the fourth, 1999, edition of the International Code of Zoological Nomenclature.

After January 1, 2000, a scientific name may be formally declared to be a nomen oblitum when it has not been used in the scientific community since 1899, and when it is either a senior synonym (there is also a more recent name which applies to the same taxon, and which is in common use) or a homonym (it is spelled the same as another name, which is in common use). Once its has formally been declared be a nomen oblitum, the disused name is to be 'forgotten'. By the same act, the junior name must be declared to be a nomen protectum; from then on it takes precedence,

In the first and second editions of the zoological Code (valid between November 6, 1961 and January 1, 1973) the term was also used, but names then indicated as such do not have the same status. A notable example of this previous use is that of Scrotum humanum.