Crossword clues for the word: FEMTO The word FEMTO has appeared as an answer to at least 4 crossword clues on different crossword puzzles. Crossword clues for FEMTO Showing 1 to 4 of 4 results Clue(s) One quadrillionth: Prefix One-quadrillionth: Comb. form Prefix for a quadrillionth Quadrillionth (Prefix)