Sahaptian (also Sahaptianic, Sahaptin, Shahaptian) is a two-language branch of the hypothetical Plateau Penutian family spoken by Native American peoples in the Columbia Plateau region of Washington, Oregon, and Idaho in the northwestern United States.

The terms Sahaptian (the family) and Sahaptin (the language) have often been confused and used interchangeably in the literature.

Sahaptian includes two languages: Nez Perce has two principal dialects, Upper and Lower.

Sahaptin has somewhat greater internal diversity, with its main dialects being Umatilla and Yakama.

[1] Work on Proto-Sahaptian reconstruction has been undertaken by Aoki (1962) and Noel Rude (2006,[2] 2012[1]).