Spacecraft in the Star Trek franchise usually feature warp-drive nacelles.
Like many aviation terms, the word comes from French, in this case from a word for a small boat.
Look up nacelle in Wiktionary, the free dictionary.
^Ilan Kroo, Professor of Aeronautics and Astronautics (April 13, 1999). "Nacelle Design and Sizing". Aircraft Aerodynamics and Design Group at Stanford University. Archived from the original on March 7, 2001. Retrieved April 22, 2011.