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 ); 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

Instead of costly doubles threatening to derail his progress, there was a flurry of birdies late in a sensational second round which helped McIlroy accelerate away from the chasing pack.

From BBC • Apr. 10, 2026

“Don’t let one or two small failures in life derail you from your bigger goals.”

From MarketWatch • Apr. 7, 2026

During the early 2010s Arab Spring, elevated oil prices didn’t derail Malaysia’s growth, and banks maintained solid asset quality, he notes.

From The Wall Street Journal • Mar. 30, 2026

“The move comes amid concerns that escalating tensions could derail global growth, a backdrop that has triggered the largest two-day decline in U.S. equities in a year,” the bank added.

From Barron's • Mar. 30, 2026

Cat wanted to turn the conversation back to her grandparents, but it was impossible to derail the hundredth round of Sharks: Friends or Enemies.

From "Caterpillar Summer" by Gillian McDunn

Related Words

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