Definition of "derailleur" [derailleur]

• A device for shifting gears on a bicycle by moving the chain between sprocket wheels of different sizes. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "However, in retrospect it may be a good thing I didn't since the derailleur was the only thing that kept the rear wheel from ejecting completely."
• "The front derailleur, which is shaped like the blade of a vegetable peeler, guides the chain between the gears attached to the pedals."
• "Each appears to be different in its own way from the usual "derailleur", but who am I to judge one's special love for vowels?"