What is the correct spelling for MACH9?

If you're searching for the correct spelling of "mach9", you may actually mean "Mach 9". When referring to the speed of sound, the accurate term is Mach, capitalized, followed by a space and the corresponding number. So, Mach 9 is the correct way to express it.

Correct spellings for MACH9

  • macho He acts all macho, but he's really just scared.
  • much I didn't eat much last night because I wasn't very hungry.