Crossword clues for the word: THORIUM The word THORIUM has appeared as an answer to at least 6 crossword clues on different crossword puzzles. Crossword clues for THORIUM Showing 1 to 6 of 6 results Clue(s) Element #90 Element in vacuum tube filaments Element number 90 Metal that's an effective radiation shield Radioactive element Soft silvery-white element; symbol Th