In zoology

Zoology

Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...

, the Principle of Homonymy is one of the guiding principles of the International Code of Zoological Nomenclature

International Code of Zoological Nomenclature

The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...

.

It states that any one name, in one particular spelling, may be used only once (within its group). This will be the first-published name; any later name with the same spelling (a homonym

Homonym (zoology)

In biology, a homonym is a name for a taxon that is identical in spelling to another such name, that belongs to a different taxon.The rule in the International Code of Zoological Nomenclature is that the first such name to be published is the senior homonym and is to be used ; any others are junior...

) is barred from being used. The Principles of Priority

Principle of Priority

thumb|270px|Boa manditraIn zoology, the scientific study of animals, the Principle of Priority is one of the guiding principles of the International Code of Zoological Nomenclature, defined by Article 23....

 and the First Reviser

Principle of the First Reviser

In zoology, the Principle of the First Reviser is one of the guiding principles of the International Code of Zoological Nomenclature.It supplements the Principle of Priority, which states that the first published name takes precedence...

 apply here. For family-group names the termination (which is rank-bound) is not taken into account.

In 1777 Johann Reinhold Forster

Johann Reinhold Forster

Johann Reinhold Forster was a German Lutheran pastor and naturalist of partial Scottish descent who made contributions to the early ornithology of Europe and North America...

 published the name Echidna for a genus of moray eel

Moray eel

Moray eels are cosmopolitan eels of the family Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine, but several species are regularly seen in brackish water and a few, for example the freshwater moray can sometimes be found in freshwater...

s. This meant that when Georges Cuvier

Georges Cuvier

Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...

 proposed to use this name Echidna in 1797 for the spiny anteater

Echidna

Echidnas , also known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. There are four extant species, which, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs...

 he created a junior homonym. Later, in 1811, Johann Karl Wilhelm Illiger

Johann Karl Wilhelm Illiger

Johann Karl Wilhelm Illiger was a German entomologist and zoologist.Illiger was the son of a merchant in Brunswick. He studied under the entomologist Johann Hellwig, and later worked on the zoological collections of Johann Centurius Hoffmannsegg...

 published the name Tachyglossus, as a replacement name, or nomen novum

Nomen novum

In biological nomenclature, a nomen novum , new replacement name is a technical term...

, and this is considered to be the valid name

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...

for the spiny anteater.