Word Origin & History
Appaloosabreed of horses favored by Indian tribes in U.S. West, 1849, either from Opelousa in Louisiana or from Palouse Indians, who lived near river of that name in Idaho, in which case it is probably 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."