The story
- Chinook Jargon · borrowed fromTlamatl“either "swiftness" or "they of the river"”
- English todayKlamath
From Chinook Jargon Tlamatl (“either "swiftness" or "they of the river"”), with the first syllable's onset consonant cluster dissimilated and the coda of the second syllable changed to the somewhat similar-sounding interdental fricative during the process of anglicization.
Etymology from Wiktionary, CC BY-SA 4.0.