de·rail·leur 
(dĭ-rālər)
(dĭ-rālər)n.
A device for shifting gears on a bicycle by moving the chain between sprocket wheels of different sizes.
[French dérailleur, from dérailler, to derail; see DERAIL.]
- natural number
- natural philosopher
- natural philosophy
- natural resource
- natural rubber latex
- natural science
- natural scientist
- natural selection
- natural theology
- natural virtue
- nature
- natured
- nature trail
- naturism
- naturist
- naturopath
- naturopathic
- naturopathy
- Naucratis
- Naugahyde
- Naugatuck River
- naught
- naughtily
- naughtiness
- naughty