[ 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 Unabridged Dictionary, © Random House, Inc. 2020

Examples from the Web for derail

British Dictionary definitions for derail

/ (dɪˈreɪl) /


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 forms of derail

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