RADIOTHORIUM Scrabble 18 Words With Friends 19 Scrabble letter values: R1A1D2I1O1T1H4O1R1I1U1M3 = 18 Definition noun radioactive isotope of thorium with mass number 228. — synonyms: thorium-228 See all 320 words you can make from RADIOTHORIUM → 12-letter words Words starting with R Words ending with M ← Unscramble different letters