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[dee-reyl] /diˈreɪl/
verb (used with object)
to cause (a train, streetcar, etc.) to run off the rails of a track.
to cause to fail or become deflected from a purpose; reduce or delay the chances for success or development of:
Being drafted into the army derailed his career for two years.
verb (used without object)
(of a train, streetcar, etc.) to run off the rails of a track.
to become derailed; go astray.
a track device for derailing rolling stock in an emergency.
Origin of derail
1840-50; < French dérailler, equivalent to dé- dis-1 + -railler, verbal derivative of rail rail1 (< E) Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for derail
Contemporary Examples
Historical Examples
  • I had no dynamite with me, and I could neither blow it up nor derail it.

    Three Years' War

    Christiaan Rudolf de Wet
  • That would delay it or derail it, and neither option is acceptable.

  • To add to the traveller's discomfort, the road-bed is as bad as it can be and not derail the cars constantly.

    Under the Southern Cross Maturin M. Ballou
  • He knew for a certainty whose plantations he might traverse, and whose fences he might derail.

    Bayou Folk Kate Chopin
  • Stopping the engine they fitted it into the track in such a way that it seemed certain to derail the Confederate engine.

British Dictionary definitions for derail


to go or cause to go off the rails, as a train, tram, etc
(mainly US) Also called derailer. a device designed to make rolling stock or locomotives leave the rails to avoid a collision or accident
Derived Forms
derailment, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for derail

1850, in both transitive and intransitive senses, from French dérailler "to go off the rails," from de- (see de-) + railler (see rail (n.1)). In general use first in U.S. Related: Derailed; derailing.

Online Etymology Dictionary, © 2010 Douglas Harper
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Slang definitions & phrases for derail



To throw off the proper course; wreck: He managed to derail the proposal just before Christmas

[1950s+; The source term, ''To leave or cause a car or engine to leave the railroad tracks,'' was adopted fr French by 1850]

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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