Plain English Meaning
The engines on an aircraft, along with the parts that make them run.
Full Definition
In aviation, the engines that produce the thrust or power needed to propel an aircraft, together with the components directly required for their operation such as the propeller (if fitted), fuel and oil systems, ignition, and accessories.
Context Anchor
Seen in aircraft systems, maintenance training, aircraft inspections, and discussions of engine operation.
Derivation
From 'power' (the energy to do work) and 'plant' (an industrial installation that produces something). Together, a '' is the installation that produces motive power. The aviation use carries this meaning from ships and factories: the engine is the 'plant' that generates power for the aircraft.