Yaak is an unincorporated community and census-designated place in Lincoln County, Montana, United States. It is located along the Yaak River, within the Kootenai National Forest. As of the 2020 census, its population was 338. Yaak has frequently been noted on lists of unusual place names. Yaak derives its name from the Yaak River. According to local lore, A’ak is a Kootenai name meaning “Arrow.” The Kootenai River forms the shape of a drawn bow; its tributary the Yaak River is its arrow.