Yes, CHINOOKS is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, I 1, N 1, O 1, O 1, K 5, S 1.

Is it a valid word?

CHINOOKS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a warm dry wind blowing down the eastern slopes of the Rockies
a member of an important North American Indian people who controlled the mouth of the Columbia river; they were organized into settlements rather than tribes
pink or white flesh of large Pacific salmon
a Penutian language spoken by the Chinook
large Pacific salmon valued as food; adults die after spawning

Also: chinook wind, snow eater, chinook salmon, king salmon, quinnat salmon, oncorhynchus tshawytscha.

Not playable in Scrabble US: CHINOOKAN.