KlamathPronunciation: /ˈklaməθ/Definition of Klamath noun (plural same or Klamaths) 1a member of an American Indian people of the Oregon-California border. 2 [mass noun] the Penutian language of the Klamath, now extinct or very nearly so. adjective relating to the Klamath or their language. Origin:from ChinookKlamath in other Oxford dictionaries Definition of Klamath in the US English dictionary