Meaning of "Mach meter"

an instrument in an aircraft indicating airspeed as a Mach number.

Mach·me·ter

mäk′mē′tər
Mach·me·ter  (mäk′mē′tər)
n.
An aircraft instrument that indicates speed in Mach numbers.

Machmeter

ˈmækˌmiːtə
Machmeter (ˈmækˌmiːtə)
n
(Aeronautics) an instrument for measuring the Mach number of an aircraft in flight