Yes, YAHOOS is a Scrabble word!

Letter values in Scrabble US: Y 4, A 1, H 4, O 1, O 1, S 1.

Is it a valid word?

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

a person who is not very intelligent or interested in culture
one of a race of brutes resembling men but subject to the Houyhnhnms in a novel by Jonathan Swift
a widely used search engine for the web that finds information, news, images, products, finance