NGS Style Manual - A -

The terms American Indian, Indian, and Native American are all acceptable and can be used interchangeably, although Native American, a broader term, may include Aleuts and Eskimos. Be sensitive to individual preference when using these terms and whenever possible use a specific group or tribal name.

For a specific group follow the spelling in Webster's or the Style Manual. For tribal plurals do not add s: Comanche, Cuna, Shoshone, Aztec, Maya; for individuals, s may be added: three Comanches. But a Blackfeet, the Blackfeet nation, the Blackfeet in U.S. context.

See also Amerindian.