or Mach number
a number indicating the ratio of the speed of an object to the speed of sound in the medium through which the object is moving. Abbreviation: M
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Also called mach, Mach [mahk] /mɑk/ .
Origin of mach number
First recorded in 1935–40; after Ernst Mach
Words nearby mach number
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020
British Dictionary definitions for mach number
(often not capital) the ratio of the speed of a body in a particular medium to the speed of sound in that medium. Mach number 1 corresponds to the speed of soundOften shortened to: Mach
Word Origin for Mach number
C19: named after Ernst Mach
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
Scientific definitions for mach number
The ratio of the speed of a body to the speed of sound in a particular medium, usually the Earth's atmosphere. For example, an aircraft flying through air at twice the speed of sound has a Mach number of 2. The Mach number of an aircraft travelling at a given velocity depends on the altitude of the aircraft and other atmospheric conditions that affect the speed of sound near the aircraft. See also subsonic supersonic transonic.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Cultural definitions for mach number
[ (mahk) ]
The speed of an object, measured in multiples of the speed of sound. Thus, an airplane traveling at the speed of sound is said to be at Mach 1; at twice the speed of sound, it is said to be at Mach 2.
notes for Mach number
The unit is named after Ernst Mach, an Austrian physicist of the nineteenth century.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.