| Answer | Crossword Clue |
|---|---|
| subsonic | moving at a speed less than that of sound |
| subsonically | SUBSONIC, moving at a speed less than that of sound |
| subsonic | noting or pertaining to a speed less than that of sound in air at the same height above sea level |
| supersonic | a wave or frequency moving at a speed greater than the speed of sound in air |
| supersonics | SUPERSONIC, a wave or frequency moving at a speed greater than the speed of sound in air |
| hypersonic | flying at more than five times the speed of sound |
| hypersonically | HYPERSONIC, flying at more than five times the speed of sound |
