The Cowlitz language is a member of the Tsamosan (Olympic) branch of the Coast Salish

Coast Salish

Coast Salish languages are a subgroup of the Salishan language family. These languages are spoken by First Nations or Native American peoples inhabiting the territory that is now the southwest coast of British Columbia around the Strait of Georgia and Washington state around Puget Sound...

 family of Salishan languages

Salishan languages

The Salishan languages are a group of languages of the Pacific Northwest...

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The Cowltiz tribe

The 'Cowlitz tribe' was originally two distinct tribes: the Lower Cowlitz and the Upper Cowlitz. Only the Lower Cowlitz spoke Cowlitz; the Upper Cowlitz, a Sahaptin tribe, spoke a dialect of Yakama.

Vocabulary

Cowlitz is most similar to Lower Chehalis, another Tsamosan language, although it does contains some oddities, such as the word for one, utsus (in contrast to the Lower Chehalis paw).

English	Cowlitz
Lower Cowlitz tribe	Sł'púlmš
one (number)	utsus
two	salli
three	kałi
four	mus