Definition 1 of 2
Plain English Meaning
A small device fitted at the thing being measured. It senses a value like fuel level or oil temperature and sends an electrical signal to the gauge on the panel so the pilot can read it from the cockpit.
Full Definition
The transmitting component of a remote-indicating system. The sender is mounted at the location being measured (such as a fuel tank, engine, or hydraulic line) and converts a physical quantity — fuel level, pressure, temperature, or position — into an electrical signal that is sent to a matching indicator on the instrument panel.
Context Anchor
Seen in aircraft instrument, engine, and discussions, especially when a gauge reading is being checked or a system is being troubleshot.