Crossword clues for the word: THALLIUM The word THALLIUM has appeared as an answer to at least 3 crossword clues on different crossword puzzles. Crossword clues for THALLIUM Showing 1 to 3 of 3 results Clue(s) Element used in thermometers Poison stunted the leek? Soft silvery-white metallic element; symbol Tl