Gros Ventre (grō văN´trə) [Fr.,=big belly], name used by the French for two quite distinct Native North American groups. One was the Atsina, a detached band of the Arapaho, whose language belongs to the Algonquian branch of the Algonquian-Wakashan linguistic stock (see Native American languages); the other was the Hidatsa, whose language belongs to the Siouan branch of the Hokan-Siouan linguistic stock. The Native American sign language designated the two groups by somewhat similar gestures on the torso, one referring to the Hidatsa chest tattoos and the other, designating the Atsina, conveying the meaning of hunger. In the 18th cent. the Atsina roamed the plains between the Missouri and the Saskatchewan rivers under the protection of the powerful Blackfoot to the west. Today the Atsina live with the Assiniboin on the Fort Belknap Reservation in Montana, established in 1888. There were some 2,800 Atsina in the United States in 1990.
See R. Flannery, The Gros Ventres of Montana (2 vol., 1953–57).