breed of horses favored by Indian tribes in U.S. West, 1849, either from Opelousa in Louisiana or from Palouse Indians, who lived near the river of that name in Idaho, in which case it probably is a Nez Percé word. Opelousa is perhaps from Choctaw api losa "black body;" while Palouse is from Sahaptin palou:s "what is standing up in the water."