Crossword clues for the word: SUBSONIC The word SUBSONIC has appeared as an answer to at least 5 crossword clues on different crossword puzzles. Crossword clues for SUBSONIC Showing 1 to 5 of 5 results Clue(s) At turbo-prop speed Below Mach 1 Not like an SST Slower than Mach 1 With lad in charge, coach returned at such speed? Definitely