COSIEST is a playable word

cosy Scrabble® Dictionary

adjective
cosier, cosiest
cozy
verb
cosied, cosying, cosies
to cozy
90 Playable Words can be made from "COSIEST"
   2-Letter Words (12 found)
   3-Letter Words (25 found)
   6-Letter Words (7 found)
   7-Letter Words (1 found)