Altimeter
Formal
Altimeter is an instrument used to measure the altitude of an object above a fixed level. The device’s general purpose is to tell its human or machine user how elevated from sea level it is.
Practical
An altimeter is a altitude measurement device used by mountaineers, skydivers, pilots, satellites, and many others. The device’s general purpose is to tell its human or machine user how elevated from sea level it is. It performs this function via one of two ways: either by measuring the local air pressure using a barometer, or by bouncing radar off a target.
