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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

Reaching Mach 5 involves the use of a so-called ramjet, which is similar to a traditional jet engine but doesn’t have any moving parts.

From Los Angeles Times • Apr. 7, 2026

“It goes without saying that unmanned systems are incredibly, incredibly important in future warfare,” Mach Industries founder Ethan Thornton told Barron’s in a recent interview.

From Barron's • Mar. 31, 2026

These missiles travel at Mach 5 or faster and are much more difficult to track and shoot down than conventional versions.

From The Wall Street Journal • Feb. 16, 2026

The object raced through the atmosphere at roughly Mach 25-30, moving northeast over Santa Barbara and Las Vegas at about ten times the speed of the fastest jet aircraft.

From Science Daily • Jan. 24, 2026

The fulfillment of Mach 1 fed the appetite for Mach 2.

From "Hidden Figures" by Margot Lee Shetterly