Definition
A streamlined enclosure on an aircraft that houses an engine, and sometimes other components such as fuel, landing gear, or systems equipment. The nacelle is shaped to reduce drag and is typically mounted on a wing, on the fuselage, or at the tail.
Plain English
The smooth, rounded housing around an aircraft engine. It covers the engine and helps the air flow cleanly past it.
Context Anchor
Seen in aircraft systems discussions, especially when describing engine anti-ice protection around the engine housing and front opening.
Derivation
From the French nacelle, meaning 'small boat' or 'cradle,' which itself comes from the Latin navicella, a diminutive of navis ('ship'). The aviation use carries that same idea of a shaped shell that cradles something inside it -- in this case, the engine.
Why Pilots Care
Ice buildup on nacelles can disrupt airflow into the engine and reduce thrust, making reliable anti-icing systems essential for safe operation in icing conditions.
Intuition Check
A nacelle is not the engine itself. It is the outside housing or pod that surrounds the engine or equipment.
Example Sentence 1
During the preflight walk-around, the pilot checked each nacelle for oil streaks and made sure all access panels were secured.
Example Sentence 2
During the preflight inspection, the pilot checked the de-icing boots installed on both wing leading edges and engine nacelles.