SUBRULES is a playable word

subrule Scrabble® Dictionary

noun
pl. subrules
a subordinate rule
90 Playable Words can be made from "SUBRULES"
   2-Letter Words (6 found)
   3-Letter Words (20 found)
   6-Letter Words (6 found)
   7-Letter Words (1 found)
   8-Letter Words (1 found)