|Native to||United States|
|Region||Southern Oregon and northern California|
|Ethnicity||170 Klamath and Modoc (2000 census)|
|Extinct||2003, with the death of Neva Eggsman|
Klamath //, also Klamath–Modoc / / and historically Lutuamian //, is a Native American language that was spoken around Klamath Lake in what is now southern Oregon and northern California. It is the traditional language of the Klamath and Modoc peoples, each of whom spoke a dialect of the language. As of April 1998[update], it was spoken by only one person. As of 2003, the last fluent Klamath speaker in Chiloquin, Oregon was 92 years old. As of 2006 there were no fluent native speakers of either the Klamath or Modoc dialects. 
Klamath is a member of the Plateau Penutian language family, which is in turn a branch of the proposed Penutian language family. Like other proposed Penutian languages, Plateau Penutian languages are rich in ablaut, much like Indo-European and Afro-Asiatic languages. Further evidence for this classification includes some consonant correspondences between Klamath and other alleged Penutian languages. For example, the Proto-Yokuts retroflexes */ʈ ʈʼ/ correspond to Klamath /tʃ tʃʼ/, and the Proto-Yokuts dentals */t̪ t̪ʰ t̪ʼ/ correspond to the Klamath alveolars /t tʰ tʼ/.
|Close||i ~ ɪ||iː|
|Open-mid||e ~ ɛ||ɛː||o ~ ɔ||ɔː|
|Open||a ~ ɑ||ɑː|
Most consonants can be geminated. The fricative /s/ is an exception, and there is evidence suggesting this is a consequence of a recent sound change. Albert Samuel Gatschet recorded geminated /sː/ in the late 19th century, but this sound was consistently recorded as degeminated /s/ by M. A. R. Barker in the 1960s. Sometime after Gatschet recorded the language and before Barker did the same, */sː/ may have degeminated into /s/.
Klamath word order is conditioned by pragmatics. There is no clearly defined verb phrase or noun phrase. Alignment is nominative–accusative, with nominal case marking also distinguishing adjectives from nouns. Many verbs obligatorily classify an absolutive case. There are directive and applicative constructions.
- Klamath at Ethnologue (18th ed., 2015)
- Lane, Valeree. "Chiloquin man helps Klamath Tribal members embrace first language". Herald and News. Retrieved 2018-03-01.
- Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, eds. (2017). "Klamath-Modoc". Glottolog 3.0. Jena, Germany: Max Planck Institute for the Science of Human History.
- Laurie Bauer, 2007, The Linguistics Student’s Handbook, Edinburgh
- Chen, 1998; Maudlin, 1998.
- Haynes, Erin F. "Obstacles facing tribal language programs in Warm Springs, Klamath, and Grand Ronde" (PDF). Coyote Papers. 8: 87–102. Archived from the original (PDF) on 2010-07-09. Retrieved 2012-08-30.
- Golla, Victor. (2011). California Indian Languages. Berkeley/Los Angeles, California : University of California Press. ISBN 9780520266674
- "Language - Klamath Tribes". klamathtribes.org. The Klamath Tribes. Retrieved May 2, 2018.
- Blevins, 2004, p. 279.
- Blevins, 2004, pp. 279–80.
- Blevins, 2004.
- Rude, 1988.
- Barker, M. A. R. (1963a). Klamath Texts. University of California Publications in Linguistics, volume 30. Berkeley/Los Angeles: University of California Press.
- ———. (1963b). Klamath Dictionary. University of California Publications in Linguistics 31. Berkeley/Los Angeles: University of California Press.
- ———. (1964). Klamath Grammar. University of California Publications in Linguistics 32. Berkeley/Los Angeles: University of California Press.
- Barker, Philip. (1959). The Klamath language. Dissertation, University of California, Berkeley
- Blevins, J. (2004, July). Klamath sibilant degemination: Implications of a recent sound change. IJAL, 70, 279–289.
- Chen, D. W. (1998, April 5). Blackboard: Lost languages; Kuskokwim not spoken here. New York Times.
- de Angulo, Jaime (1931). The Lutuami language (Klamath-Modoc). Société des Américanistes. Retrieved 2012-08-30.
- Maudlin, W. S. (1998, April 17). Yale linguists part of effort to save dying languages. The Yale Herald. Retrieved May 6, 2008
- Rude, Noel (1987). Some Sahaptian-Klamath grammatical correspondences. Kansas Working Papers in Linguistics, 12:67-83.
- Rude, Noel (1988). Semantic and pragmatic objects in Klamath. In In Honor of Mary Haas: From the Haas Festival Conference on Native American Linguistics, ed. by William Shipley, pp. 651–73. Berlin: Mouton de Gruyter.
- Rude, Noel (1991). Verbs to promotional suffixes in Sahaptian and Klamath. In Approaches to Grammaticalization, ed. by Elizabeth C. Traugott and Bernd Heine. Typological Studies in Language 19:185-199. New York and Amsterdam: John Benjamins Publishing Company.
- Coville, Frederick Vernon (1897). Notes on the plants used by the Klamath Indians of Oregon. Retrieved 2012-08-30. Includes Klamath language plant names.
- Gatschet, Albert S. (1890). "The Klamath Indians of southwestern Oregon". Retrieved 2012-08-30.
- Gatschet, Albert S. (1880). The numeral adjective in the Klamtah language of southern Oregon. Retrieved 2012-08-30.
- Gatschet, Albert S. (1878). "Sketch of the Klamath language of Southern Oregon". Retrieved 2012-08-30.
- The Klamath Tribes Language Project
- Languages of Oregon: Klamath
- Klamath-Modoc language, native-languages.org
- Modoc language overview at the Survey of California and Other Indian Languages
- Klamath language, California Language Archive
- OLAC resources in and about the Klamath-Modoc language
- Klamath Bibliography