MUONIUM is a playable word

muonium Scrabble® Dictionary

noun
pl. muoniums
an electron and a positive muon bound together
29 Playable Words can be made from "MUONIUM"
   2-Letter Words (12 found)
   3-Letter Words (11 found)
   4-Letter Words (4 found)
   5-Letter Words (1 found)
   7-Letter Words (1 found)