Siouan languages
Authors who call the entire family "Siouan" distinguish the two branches as "Western Siouan" and "Eastern Siouan" or as "Siouan-proper" and "Catawban". Others restrict the name "Siouan" to the western branch and use the name "Siouan–Catawban" for the entire family. Generally, however, the name "Siouan" is used without distinction.
Sioux language
Closely related to the Sioux language are the Assiniboine and Stoney languages, whose speakers use the self-designation term (autonym) "Nakhóta" or "Nakhóda". Speakers of Lakota and Dakota have more difficulty understanding each of the two Nakoda languages (Assiniboine and Stoney).