derailleur /dɪˈreɪlɚ/ noun
plural derailleurs
derailleur
/dɪˈreɪlɚ/
noun
plural derailleurs
Learner's definition of DERAILLEUR
[count]
: a part on a bicycle that is used to change gears by moving the chain from one gear to another one(自行车的)变速器 — see picture at bicycle