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

In that scenario, “energy prices haven’t risen enough to derail a resilient economy, but they have risen enough to reinforce inflation dynamics,” Luzzetti said.

From MarketWatch • May 30, 2026

Tehran’s signaled that the strikes wouldn’t derail talks, while U.S.

From The Wall Street Journal • May 27, 2026

Twisha's father has questioned both the post-mortem report and the police investigation, insisting that his daughter was murdered and alleged that "influential people are trying to derail the investigation".

From BBC • May 21, 2026

But nothing can derail the success of this extraordinary production, the high watermark so far of Pasadena Playhouse producing artistic director Danny Feldman’s ongoing reexamination of the American musical canon.

From Los Angeles Times • May 20, 2026

Just be sure not to derail them in the middle of a train of thought.

From "The Sense of Style" by Steven Pinker

Related Words

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