nounpl. Assiniboin or As·sin·i·boins also Assiniboine or As·sin·i·boines
- A member of a Native American people formerly inhabiting southern Manitoba, now located in Montana, Alberta, and Saskatchewan. The Assiniboin became nomadic buffalo hunters after migrating to the northern Great Plains in the 18th century.
- The Siouan language of the Assiniboin. In both senses also called Nakota. See Usage Note at Nakota.
Origin of AssiniboinFrench Assiniboine, of Ojibwa origin.