Crossword clues for the word: UNSOUND The word UNSOUND has appeared as an answer to at least 9 crossword clues on different crossword puzzles. Crossword clues for UNSOUND Showing 1 to 9 of 9 results Clue(s) "Fallacious, as an argument" "Not good, as ideas go" Apt to break Faulty, as a plan Likely to fail Not firm, as a foundation Prone to injury Rickety, say Specious.