Plain English Meaning
The part that pushes fuel from the tanks to the engine. There is usually a main one driven by the engine itself, plus an electric backup the pilot can switch on.
Full Definition
A device that moves fuel from the aircraft's fuel tanks to the engine at the pressure and flow rate the engine requires. Most piston aircraft have two: an engine-driven pump that operates whenever the engine is running, and an electric auxiliary (boost) pump used for starting, takeoff, landing, and as a backup if the engine-driven pump fails.
Context Anchor
You will see this term during preflight inspection, engine start, takeoff checks, and discussions of the airplane fuel system.
Why Pilots Care
A failing fuel pump can cause loss of engine power or complete engine stoppage, so pilots verify its condition and operation before every flight.
Intuition Check
A fuel pump is not the airport pump used to put fuel into the airplane. In this context, it means a pump installed in the airplane that helps deliver fuel to the engine.
Example Sentence 1
Before starting the engine, the pilot turned on the electric fuel pump and checked that fuel pressure rose into the green arc.
Example Sentence 2
Once the engine started, the engine-driven fuel pump took over supplying fuel to the carburetor.