n. pl.; sing. Dacota /sing>. (Ethnol.) An extensive race or stock of Indians, including many tribes, mostly dwelling west of the Mississippi River; -- also, in part, called Sioux. [ Written also Dacotahs. ] [ 1913 Webster ]
(Geol.) A subdivision at the base of the cretaceous formation in Western North America; -- so named from the region where the strata were first studied. [ 1913 Webster ]
(n) a member of the large western branch of Sioux people which was made up of several groups that lived on the plains, Syn. Teton Sioux, Teton Dakota, Lakota