STIFFEST is a playable word

stiff Scrabble® Dictionary

adjective
stiffer, stiffest
difficult to bend or stretch
verb
stiffed, stiffing, stiffs
to cheat someone by not paying
74 Playable Words can be made from "STIFFEST"
   2-Letter Words (10 found)
   3-Letter Words (21 found)
   6-Letter Words (3 found)
   8-Letter Words (1 found)