Pronunciation: (u-sin'u-boin"), [key]
—pl. -boins, (esp. collectively) -boin.
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.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.