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• mach
  mach

  noun

  mach number.
• Mach
  Mach

  noun

  Ernst 1838–1916, Austrian physicist, psychologist, and philosopher.
• mach.
  mach.

  abbreviation

  machine.

mach

¹ American  

[mahk] / mɑk /

Or Mach

noun

1. mach number.

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Mach ² American  

[mahk, mahkh] / mɑk, mɑx /

noun

1. Ernst 1838–1916, Austrian physicist, psychologist, and philosopher.

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mach. ³ American  

abbreviation

1. machine.

2. machinery.

3. machinist.

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Mach ¹ British  

/ mæk /

noun

1. short for Mach number

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Mach ² British  

/ max /

noun

1. 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

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Mach Scientific  

/ mäk,mäkh /

1. 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.

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Usage

How fast is Mach 1? A Mach number is the ratio of an object's speed in a given medium to the speed of sound in that medium. Mach 1, then, is the speed of sound, around 761 mph at sea level on a standard day. The term is also used as a metaphor for high speeds more generally. How to pronounce Mach 1[ mahk wuhn ]

Etymology

Origin of mach

After Ernst Mach

Example Sentences

Hypersonic means Mach 5—five times the speed of sound.

From The Wall Street Journal • Jun. 14, 2026

The funding will help Mach Industries expand its manufacturing, advance its technology and deepen its partnerships with customers that include the U.S.

From Los Angeles Times • Jun. 3, 2026

For Exquadrum’s gray-haired founders, the business and political realities that helped a startup like Mach amass a $200 million war chest in three years are a new phenomenon.

From The Wall Street Journal • May 19, 2026

Beyond supersonic travel lies hypersonic travel, which involves flying at Mach 5 or above and comes with intense thermal challenges that have yet to be resolved.

From The Wall Street Journal • May 15, 2026

With Mach 1 achieved, engineering imaginations broke free of all previous speed limits.

From "Hidden Figures" by Margot Lee Shetterly