RUBIDIUM /ˌɹuːˈbɪd.i.əm/ Scrabble 13 Words With Friends 17 Definition noun a soft silvery metallic element of the alkali metal group. — synonyms: Rb, atomic_number_37 See all 39 words you can make from RUBIDIUM → 8-letter words Words starting with R Words ending with M ← Unscramble different letters