/ dɪˈreɪl; NAmE / verb
( of a train ) to leave the track; to make a train do this :
[ v ]
The train derailed and plunged into the river.
[ vn ] ( figurative )
This latest incident could derail the peace process.
► de·rail·ment noun [ C , U ]
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WORD ORIGIN
mid 19th cent.: from French dérailler , from dé- (expressing removal) + rail rail.