derail

American  

[dee-reyl] / diˈreɪl /

verb (used with object)

1. to cause (a train, streetcar, etc.) to run off the rails of a track.

2. 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.

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verb (used without object)

1. (of a train, streetcar, etc.) to run off the rails of a track.

2. to become derailed; go astray.

noun

1. a track device for derailing rolling stock in an emergency.

derail British  

/ dɪˈreɪl /

verb

1. to go or cause to go off the rails, as a train, tram, etc

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noun

1. Also called: derailer.  a device designed to make rolling stock or locomotives leave the rails to avoid a collision or accident

Other Word Forms

• derailment
  noun

Etymology

Origin of derail

First recorded in 1840–50; from French dérailler, equivalent to dé- negative prefix + -railler, verbal derivative of rail “bar, beam” (from English ); see origin at de- rail ¹

Explanation

When a train or a subway derails, its wheels accidentally leave the tracks. Train cars that derail can cause the cars behind them to crash. Mistakes by engineers or flaws in the track can derail a train or trolley, sending it off the rails and sometimes injuring the passengers. You can also use the verb derail figuratively, to mean "hinder someone" or "divert a process from going in its intended direction." For example, terrorists might derail ongoing peace talks by blowing up a bus. The word comes from the French dérailler, "go off the rails."

Example Sentences

Appeared in the January 8, 2026, print edition as 'Rate Worries Derail Dow’s Rally'.

From The Wall Street Journal • Jan. 7, 2026

A version of this article appears in print on March 2, 2014, on page SP3 of the with the headline: Late Scoring Drought Can’t Derail Connecticut.

From New York Times • Mar. 1, 2014

Why Rising Bullishness Could Derail Stocks The market might be far from the euphoria that often coincides with the end of a rally.

From BusinessWeek • Apr. 26, 2010

Speaking of Detour and Derail, “I wonder,” wonders A. T., “whether in your travels you ever got to Goslow.”

From The So-called Human Race by Taylor, Bert Leston

Derail, de-rāl′, v.t. to cause to leave the rails.—n.

From Chambers's Twentieth Century Dictionary (part 1 of 4: A-D) by Various

Related Words

• block
• deter
• filibuster
• hamper
• hinder
• impede
• interfere
• stall
• stonewall
• thwart