The state of having the species or subspecies name identical to the generic name of the genus in which it is placed.

Absolute tautonymy is the identical spelling of a generic or subgeneric name and the specific or subspecific name of one of its originally included nominal species or subspecies.

Linnaean tautonymy is the identical spelling of a new generic or subgeneric name established before 1931 and a pre-1758 name cited as a synonym of only one of the species or subspecies originally included in that genus.

Virtual tautonymy is the nearly identical spelling, or the same origin or meaning, of a generic or subgeneric name and the specific or subspecific name in a binomen or trinomen (not a term regulated by the International Code of Zoological Nomenclature).