Definition
Rotating airfoils mounted on the engine that produce thrust by accelerating a mass of air rearward. Each propeller blade is shaped like a small wing, and its rotation creates a pressure difference that pulls (or pushes) the airplane through the air.
Plain English
The spinning blades on the front of many small airplanes that pull the airplane forward through the air, like a fan turned sideways.
Context Anchor
Pilots encounter propellers during preflight inspection, engine start, taxi, takeoff, and any discussion of how engine power moves the airplane.
Derivation
From the Latin propellere, meaning 'to drive forward.' That captures exactly what a propeller does — it drives the airplane forward through the air.
Why Pilots Care
Propellers produce the thrust needed for takeoff, climb, and cruise in most piston-engine airplanes; their condition and pitch settings directly affect performance and safety.
Intuition Check
Do not think of propellers as just airplane fans. A fan mainly moves air for airflow; an aircraft propeller is designed to create the force that moves the airplane.
Example Sentence 1
Before starting the engine, the pilot checked that the area around the propeller was clear of people and loose objects.
Example Sentence 2
Before flight the student checked the propellers for cracks and ensured the spinner was secure.