from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Of less than audible frequency.
  • adj. Having a speed less than that of sound in a designated medium.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. having a frequency too low to be audible
  • adj. less than the speed of sound (in the same medium, and at the same temperature and pressure)

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. (of speed) less than that of sound in a designated medium


Sorry, no etymologies found.



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