1.AdjectiveOf a subspecies: nominate, having a name which repeats the species name, designating that it represents the originally described population.
" Motacilla alba alba is the nominotypical subspecies of the white wagtail (Motacilla alba)."
2.AdjectiveOf a subgenus or other infrageneric taxon: having a name which repeats the genus name, indicating that it includes the type species. For older botanical subgeneric and sectional names, it is sometimes prefixed with Eu-.