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

Thursday’s vote is a huge step forward for the crypto industry’s biggest legislative priority, but even a small hiccup could derail its path to becoming law.

From Barron's • May 14, 2026

Investors feared that the energy shock would derail a big year for international stocks, particularly in the developing world.

From The Wall Street Journal • May 3, 2026

The proposal faces multiple hurdles that could derail it.

From Los Angeles Times • Apr. 30, 2026

With Hearts going for the title and Hibs busting a gut to derail them, there was a school of thought that this was the biggest Edinburgh derby of them all in the league.

From BBC • Apr. 26, 2026

The memory is almost enough to derail Axel’s quest for his quiet bedroom and a good book.

From "A Bird Will Soar" by Alison Green Myers

Related Words

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