teton: a member of the large western branch of Sioux people which was made up of several groups that lived on the plains
sioux: a member of a group of North American Indian peoples who spoke a Siouan language and who ranged from Lake Michigan to the Rocky Mountains
principle of equivalence: (physics) the principle that an observer has no way of distinguishing whether his laboratory is in a uniform gravitational field or is in an accelerated frame of reference