Stoney—also called Nakota, Nakoda, Isga, and formerly Alberta Assiniboine—is a member of the Dakota subgroup of the Mississippi Valley grouping of the Siouan languages.

[6] Stoney is the most linguistically divergent of the Dakotan dialects[7] and has been described as "on the verge of becoming a separate language.

The Stoney form of the Nakoda language is completely unintelligible to Lakota and Dakota speakers.

[12] The two have often been confused with each other due to their close historical and linguistic relationship, but they are not mutually intelligible.

For example, the following phonemes are reportedly found in Morley Stoney, spoken on the Morley Reserve: For comparison, these phonemes reportedly characterize the Stoney spoken at Alexis Nakota Sioux Nation, which maintains the common Siouan three-way contrast[5] between plain, aspirated, and ejective stops: Notice that Alexis Stoney, for example, has innovated contrastive vowel length, which is not found in other Dakotan dialects.