SIZIEST is a playable word

sizy Scrabble® Dictionary

adjective
sizier, siziest
viscid
38 Playable Words can be made from "SIZIEST"
   2-Letter Words (7 found)
   3-Letter Words (12 found)
   4-Letter Words (10 found)
   5-Letter Words (7 found)
   7-Letter Words (2 found)