/euh sin"euh boyn'/ , n. , pl. Assiniboins , ( esp. collectively ) Assiniboin .
1. a member of a Siouan people of northeastern Montana and adjacent parts of Canada.
2. the dialect of Dakota spoken by the Assiniboin Indians.
[ 1675-85; Assiniboine assini·-pwa·n lit., stone Sioux (equiv. to Proto-Algonquian * asenyi stone + * pwa·tha enemy tribesman) ]