Definition of nacelles:
(n) :
(aviation) A separate streamlined enclosure mounted on an aircraft to house, originally, an engine, and now also cargo or crew.
(n) :
(aviation) The compartment that holds passengers on a dirigible, hot-air balloon, or other aerostat; a gondola.
(n) :
(by extension) (electrical engineering) The part between the rotor and tower of a wind turbine.
(n) :
(by extension) An enclosure housing machinery or a motor.
(n) :
(by extension) (road transport) A streamlined enclosure on the body or dashboard of a motor vehicle.
(n) :
(by extension) A hollow boat-shaped structure.