What is "tautonym"

n. (context biology informal English) A binomial name consisting of the same word twice, such as ''Bison bison''.

A tautonym is a scientific name of a species in which both parts of the name have the same spelling, for example Bison bison. The first part of the name is the name of the genus and the second part is referred to as the specific epithet in the International Code of Nomenclature for algae, fungi, and plants and the specific name in the International Code of Zoological Nomenclature.

Tautonymy (i.e., the usage of tautonymous names) is permissible in zoological nomenclature (see List of tautonyms for examples). In past editions of the zoological Code, the term tautonym was used, but it has now been replaced by the more inclusive "tautonymous names"; these include trinomial names such as Gorilla gorilla gorilla.

For animals, a tautonym implicitly indicates that the species is the type of its genus. This can also be indicated by a species name with the specific epithet typus or typicus, although more commonly the type species is designated another way.