subsonic
Americanadjective
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noting or pertaining to a speed less than that of sound in air at the same height above sea level.
adjective
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Having a speed less than that of sound in a designated medium, usually air; having a velocity less than Mach 1.
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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.
Engineers will continue conducting a mix of subsonic and lower-altitude flights to monitor the aircraft's behavior under a variety of conditions.
From Science Daily ● Jun. 1, 2026
The Burevestnik, which flew at well below the speed of sound, made its debut just as subsonic missiles are increasingly being shot down in Ukraine because modern defensive systems can lock onto them.
From The Wall Street Journal ● Oct. 28, 2025
In terms of purely destructive power, however, hypersonic missiles are not hugely different from supersonic or subsonic cruise missiles, according to Mr Freer.
From BBC ● Aug. 21, 2025
A housekeeper found three live rounds of subsonic ammunition on the floor, along with blue latex gloves, Avila said.
From Los Angeles Times ● Dec. 5, 2023
Modeling flight at transonic speeds was a particularly knotty problem, because of the subsonic and supersonic winds that passed over the plane or model simultaneously.
From "Hidden Figures" by Margot Lee Shetterly
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.
