Cayuse was a language isolate (a language unrelated to any other known living language) once spoken in the northwest United States. Though the
Cayuse people still live on combined reservations in Oregon and Washington state, their native language has not been spoken since the 19th century.
Some Cayuse Indians still speak Nez Perce, the language of a neighboring tribe with whom
many of them took shelter in the 1800's. The Cayuse language itself has left few traces. It was once said to be related to
Molalla, but this was apparently just a rumor retold as fact; the records that remain
of the language do not seem to have anything in common with Molalla or the Sahaptin languages at all.