Mach is used as a unit of measurement in stating the speed of a moving object in relation to the speed of sound. For example, if an aircraft is travelling at Mach 1, it is travelling at exactly the speed of sound.
[technical]
The hot air permitted higher speeds before the critical Mach number was exceeded.
The aim is to fly at about Mach 2, twice the speed of sound.
Mach in British English1
(mæk)
noun
short for Mach number
Mach in British English2
(German max)
noun
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