RUBIDIUMS is a playable word

rubidium Scrabble® Dictionary

noun
pl. rubidiums
a metallic element
(adjective) rubidic
102 Playable Words can be made from "RUBIDIUMS"
   2-Letter Words (8 found)
   6-Letter Words (5 found)
   7-Letter Words (1 found)
   8-Letter Words (1 found)
   9-Letter Words (1 found)