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The Collaborative International Dictionary
Douglas Harper's Etymology Dictionary

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


Mach may refer to:

Mach (kernel)

Mach is a kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computing. Mach is often mentioned as one of the earliest examples of a microkernel. However, not all versions of Mach are microkernels. Mach's derivatives are the basis of the modern operating system kernels in GNU Hurd and Apple's operating systems macOS, iOS, tvOS and watchOS.

The project at Carnegie Mellon ran from 1985 to 1994, ending with Mach 3.0, which is a true microkernel. Mach was developed as a replacement for the kernel in the BSD version of Unix, so no new operating system would have to be designed around it. Experimental research on Mach appears to have ended, although Mach and its derivatives exist within a number of commercial operating systems. These include NeXTSTEP and OpenStep, upon which macOS is based—all using the XNU operating system kernel which incorporates an earlier, non-microkernel, Mach as a major component. The Mach virtual memory management system was also adopted in 4.4BSD by the BSD developers at CSRG, and appears in modern BSD-derived Unix systems, such as FreeBSD.

Mach is the logical successor to Carnegie Mellon's Accent kernel. The lead developer on the Mach project, Richard Rashid, has been working at Microsoft since 1991 in various top-level positions revolving around the Microsoft Research division. Another of the original Mach developers, Avie Tevanian, was formerly head of software at NeXT, then Chief Software Technology Officer at Apple Inc. until March 2006.

Mach (crater)

Mach is a large lunar crater of the class known as a walled plain. It is located on the far side of the Moon and cannot be viewed directly from the Earth. Nearby craters of note include Joule to the northeast, Mitra attached to the western outer rim, and Henyey to the southwest.

This is a prominent but eroded formation with multiple craters along the rim and interior. The crater Harvey breaks across the eastern rim, and its outer rampart spills across the interior floor of Mach. The overall shape of Mach resembles a pear, with a prominent outward bulge to the northeast. Such a bulge can be caused by a second, merged crater. The northern edge is also the most worn and overlain by impacts.

The interior of Mach is marked by several small craters, particularly in the northeastern bulge. Several craters also lie along the edges to the west and northwest. The remainder of the interior floor is relatively level, when compared to the terrain that surrounds Mach. There is a formation of central ridges near the midpoint of the crater that create a large number of unexplained magnetic anomalies. (Or at least the center if the northeastern bulge is disregarded.)

Mach lies to the northeast of the Dirichlet–Jackson Basin.

Mach (Rainbow song)

"Mach" is a song by South Korean girl group Rainbow. The song was released on October 20, 2010, and was later included on their second mini album So Girls. The song is also the group's second Japanese single. It was released on December 7, 2011 in 4 different versions: 3 limited editions (CD+DVD, CD + 28-pages photobook and CD Only + Bonus track) and a regular edition.

Mach (surname)

Mach is a surname. Notable people with the surname include:

  • Alexander Mach (1902-1980), Slovak politician
  • Brice Mach (born 1986), French rugby union player
  • Daniel Mach (born 1955), French politician
  • David Mach (born 1956), Scottish artist
  • Edmund von Mach (1870-1927), German-American writer and lecturer on art
  • Ernst Mach (1838-1916), Czech-Austrian physicist and philosopher
  • Josef Mach (1909–1987), Czech actor, screenwriter and film director
  • Petr Mach (born 1975), Czech politician

Usage examples of "mach".

Mach had told him briefly of the discovery by Stile, his father, that their exchange was causing a dangerous imbalance, so they had to spend more time in their own frames.

But if that line ceases to exist, the channel by which you and Mach communicate and exchange places will be gone, and all that you contemplate will end, and my chance to rectify the accumulated imbalance will abort.

The saucer ripped by the silver delta-winged fighter at a scant hundred yards, accelerating through Mach 2.

At Mach speeds the alien boomerangs seemed to have a hard time maneuvering with precision, but as soon as the F-16s banked and slowed the little alien probes matched velocity vectors and ripped them apart.

The rush of the magnetic railgun that launched it up to scramjet speed, the screaming blast of the engine igniting at mach seven and propelling the silvery needle faster and faster until ninety-nine percent of the atmosphere lay below it and the stars came out as hard, unwinking diamonds in the blackness of space, then the whistling descent back to the ground and the swift, precise glide onto the runway -- everything about it felt right.

The AS pilot began to throttle back the scramjet as they reached Mach 20.

Samson missile, an advanced version of the older Soviet Shaddock, travels at speeds in excess of Mach 2 and carries a warhead containing a thousand pounds of TNT.

With his wingman glued to his right, Manesh pushed the throttles to the forward stops and the Flogger accelerated to Mach 1.

The Mig broke hard to the left as the Hellfire left the outboard pylon and accelerated to just under Mach 1 Manesh put the craft in a vertical climb and began dispensing flares and chaff.

Then Mach understood: this was a self-willed Machine masquerading as a mindless one.

Base, Afterbody and Tail Regions of Twin-Engine Airplane Model with Extra Low Horizontal Tail Locations at a Speed of Mach 0.

Both balls were served crosscourt, requiring Mach to orient on the extremes rapidly.

Mach slammed them simultaneously, crosscourt, and Bane was unable to field them both.

Our first test flights will run to near Mach one with a cowling replacing the hydrogen engine.

Eight metres long, three thousand kilometre range, mach point seven zero cruising speed, one thousand kilogramme direct-impact fused HE charge.