REGULUS is a playable word

regulus Scrabble® Dictionary

noun
pl. reguluses or reguli
a mass that forms beneath the slag in a furnace
(adjective) reguline
64 Playable Words can be made from "REGULUS"
   2-Letter Words (5 found)
   3-Letter Words (17 found)
   5-Letter Words (12 found)
   6-Letter Words (3 found)
   7-Letter Words (1 found)