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 Unabridged Dictionary, © Random House, Inc. 2019

Related Words for derail

hinder, thwart, crash, wreck, deflect

Examples from the Web for derail

Contemporary Examples of derail

Historical Examples of derail

  • 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


Also called: derailer mainly US a device designed to make rolling stock or locomotives leave the rails to avoid a collision or accident
Derived Formsderailment, 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

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