Definition
An instrument that displays the pressure of a gas or liquid within a system, typically by sensing the force the fluid exerts against a diaphragm, bellows, or Bourdon tube and converting that movement into a needle reading on a calibrated dial.
Plain English
A gauge that shows how hard a gas or liquid is pushing inside a system, displayed as a number on a dial.
Context Anchor
Seen in discussions of atmospheric pressure measurement, barometers, and aircraft instruments that use air pressure to give useful readings.
Derivation
From Latin pressura, meaning a pressing or squeezing, and indicare, to point out. So a pressure indicator is literally a device that points out how hard something is pressing.
Why Pilots Care
Accurate pressure readings allow pilots to determine altitude, set altimeters, and anticipate weather changes that affect flight safety and performance.
Intuition Check
A pressure indicator is not a device that creates pressure. It is a device that shows the pressure being sensed.
Example Sentence 1
During the runup, the pilot checked the oil pressure indicator and confirmed the needle was in the green arc before advancing the throttle.
Example Sentence 2
A falling pressure indicator reading warned of an approaching weather system during the cross-country flight.