Definition
The act or means of producing a forward force that drives an aircraft through the air. In aviation, propulsion is generated by an engine-and-propeller combination, a turbojet, a turbofan, or a rocket — each of which works by accelerating a mass of air or exhaust gas rearward, producing a forward thrust on the aircraft.
Plain English
Propulsion is how an aircraft gets pushed forward. The engine throws air or hot gas backward, and that pushes the aircraft forward in response.
Context Anchor
Seen in flight history, aircraft engine discussions, propeller and jet explanations, and any description of how an aircraft moves through the air under power.
Derivation
From the Latin propulsus, meaning 'driven forward' (pro- 'forward' + pellere 'to push or drive'). The original sense — pushing something forward — is exactly what an aircraft engine does.
Why Pilots Care
Without propulsion, an aircraft cannot sustain level flight or climb. Understanding how thrust is produced helps pilots make sense of engine handling, performance limits, and what happens when power is lost.
Intuition Check
Propulsion is not the same as lift. Propulsion moves the aircraft forward; the wings produce lift when air flows over them.
Example Sentence 1
Early attempts at flight failed largely because no suitable means of propulsion existed until the lightweight gasoline engine was developed.
Example Sentence 2
Jet engines provide the propulsion needed for sustained high-speed cruising.