What word or phrase does your mother always say?
measure of speed relative to the speed of sound (technically Mach number), 1937, named in honor of Austrian physicist Ernst Mach (1838-1916).
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.
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.