Plain English Meaning
A cockpit gauge that shows how fast the airplane is going up or down, measured in feet per minute.
Full Definition
A pitot-static flight instrument that displays the airplane's rate of climb or descent in feet per minute (fpm) by sensing the rate of change in static air pressure as altitude changes.
Context Anchor
Seen on the instrument panel during cockpit checks, climbs, descents, and instrument scanning.
Derivation
Straight from the words: it indicates (shows) vertical (up-and-down) . The name describes exactly what the instrument does.