altimeter

This term refers to a specialized precision instrument used primarily in aviation and mountaineering. It carries a technical, clinical connotation, evoking images of cockpit dials, atmospheric pressure, and the critical necessity of spatial awareness during ascent or descent.

As a standard countable noun, it follows regular English pluralization rules. It is distinct from a barometer, although it utilizes barometric pressure to derive height; the altimeter is specifically calibrated to translate that pressure into a measurement of vertical distance.