What do a.m. and p.m. stand for?


[mahk] /mɑk/
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.
Also called mach number, Mach number.
Origin of mach
after E. Mach


[mahk; German mahkh] /mɑk; German mɑx/
[ernst] /ɛrnst/ (Show IPA),
1838–1916, Austrian physicist, psychologist, and philosopher.

mach. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for mach


short for Mach number


/German max/
Ernst (ɛrnst). 1838–1916, Austrian physicist and philosopher. He devised the system of speed measurement using the Mach number. He also founded logical positivism, asserting that the validity of a scientific law is proved only after empirical testing
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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Word Origin and History for mach


measure of speed relative to the speed of sound (technically Mach number), 1937, named in honor of Austrian physicist Ernst Mach (1838-1916).

Online Etymology Dictionary, © 2010 Douglas Harper
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mach in Science
  (mäk, mäKH)   
Austrian physicist and philosopher who experimented with supersonic projectiles and the flow of gases, obtaining early photographs of shock waves and gas jets. His work laid an important foundation for later developments in the science of projectiles and aeronautical design, and the Mach number and Mach bands were named for him.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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mach in Technology

An operating system kernel under development at Carnegie-Mellon University to support distributed and parallel computation. Mach is designed to support computing environments consisting of networks of uniprocessors and multiprocessors. Mach is the kernel of the OSF/1.

The Free On-line Dictionary of Computing, © Denis Howe 2010
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Related Abbreviations for mach


  1. machine
  2. machinery
  3. machinist
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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