Crossword clues for the word: UNIO The word UNIO has appeared as an answer to at least 10 crossword clues on different crossword puzzles. Crossword clues for UNIO Showing 1 to 10 of 10 results Clue(s) Fresh-water mussel. Freshwater mussel Genus of mussels. Mussel genus (or a marriage cut short?) Mussel genus. Mussel used by button makers Mussel. Pearly mussel. River mussel. Unification of people or organizations: ___n