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[suhb-son-ik] /sʌbˈsɒn ɪk/
noting or pertaining to a speed less than that of sound in air at the same height above sea level.
Origin of subsonic
1940-45; sub- + -sonic
Related forms
subsonically, adverb Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for subsonic
Historical Examples
  • Most of their conversation is carried on in tones of subsonic frequency, so your ears cannot hear it.

    The Asses of Balaam Gordon Randall Garrett
  • And its booming notes descended to subsonic throbbings that gripped and wrung the nerves to anguish.

    The Record of Currupira Robert Abernathy
British Dictionary definitions for subsonic


being, having, or travelling at a velocity below that of sound: a subsonic aircraft
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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subsonic in Science
Having a speed less than that of sound in a designated medium, usually air; having a velocity less than Mach 1. Compare hypersonic, supersonic, transonic.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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