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subsonic

American  
[suhb-son-ik] / sʌbˈsɒn ɪk /

adjective

  1. noting or pertaining to a speed less than that of sound in air at the same height above sea level.

  2. infrasonic.

subsonic British  
/ sʌbˈsɒnɪk /

adjective

  1. 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
subsonic Scientific  
/ sŭb-sŏn′ĭk /

  1. Having a speed less than that of sound in a designated medium, usually air; having a velocity less than Mach 1.

  2. Compare hypersonic supersonic transonic

Other Word Forms

Etymology

Origin of subsonic

1940–45; sub- + sonic ( def. )

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Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The figure was marked “Characteristics of Flow Passage for Subsonic and Supersonic Flow Expansion and Compression.”

From "October Sky" by Homer Hickam

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.