derail

American  

[dee-reyl] / diˈreɪl /

verb (used with object)

• derails,
  present (3rd person singular)
• derailed,
  past participle,  past
• derailing
  present participle

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)

• derails,
  present (3rd person singular)
• derailed,
  past participle,  past
• derailing
  present participle

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

Derived Forms

• derailment
  noun

Inflected Forms

Participles

• derailing
  present
• derailed
  past

Conjugated Forms

Present

• derail
  simple
• derails
  simple
• have derailed
  perfect
• has derailed
  perfect
• am derailing
  progressive
• are derailing
  progressive
• is derailing
  progressive
• have been derailing
  perfect progressive
• has been derailing
  perfect progressive

Past

• derailed
  simple
• had derailed
  perfect
• was derailing
  progressive
• were derailing
  progressive
• had been derailing
  perfect progressive

Future

• will derail
  simple
• will have derailed
  perfect
• will be derailing
  progressive
• will have been derailing
  perfect progressive

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

See Examples For:

derail derails derailed derailing

And it doesn’t take a guilty verdict to derail a life.

From Los Angeles Times ● Aug. 28, 2026

But the ethical challenges shouldn’t derail the Clarity Act, Armstrong says.

From The Wall Street Journal ● Aug. 21, 2026

Video posted on social media, external showed carriages that did not derail being transported through Lewes station overnight, as recovery work continues at the site.

From BBC ● Aug. 20, 2026

“For seniors who require ongoing care, exceeding asset or income limits can delay coverage, force private pay, or derail carefully laid plans.”

From MarketWatch ● Aug. 6, 2026

Even if it may derail everything he and Mother have worked toward for so long.

From "The Adoration of Jenna Fox" by Mary E. Pearson

“I don’t see anything that derails economic or earnings growth,” said Amanda Agati, chief investment officer at PNC’s asset management group.

From Barron's ● Jul. 1, 2026

“Most people think of retirement risk in terms of market crashes,” said Jeff Judge, a certified financial planner in Forest Hill, Md. “Healthcare is the one that actually derails the most plans I’ve seen.”

From MarketWatch ● Jun. 15, 2026

Their closeness derails Rausch’s “three steps ahead” scheming.

From Salon ● Jan. 28, 2026

The train of thought derails as soon as the server at Smoke House presents a large silver tray, its display slices of cakes layered and its pies adorned with ice cream.

From Los Angeles Times ● Oct. 31, 2025

I need to get her out of here before my family derails my life just as it’s getting started.

From "The Sun Is Also a Star" by Nicola Yoon

New claims are emerging about the risks residents faced after a Norfolk Southern train carrying hazardous chemicals derailed near East Palestine.

From The Wall Street Journal ● Aug. 25, 2026

Their reunion on the field was brief — the Dodgers re-signed Heyward for the 2024 season and then, his first half derailed by injuries, released him in August — but it was still sweet.

From Los Angeles Times ● Aug. 25, 2026

The considerable momentum Alabama Shakes built was derailed, and it wasn’t entirely clear if a third LP would ever arrive.

From The Wall Street Journal ● Aug. 25, 2026

A defect was found on railway tracks in East Sussex at the site where a train derailed leaving 30 injured, a report says.

From BBC ● Aug. 19, 2026

This was her first time inside the tower, and her train of thought was derailed when she saw the furnishings.

From "City Spies" by James Ponti

“True financial independence means you reasonably control what allows you to live the life you want without external things derailing you,” Welborn said.

From MarketWatch ● Jul. 12, 2026

At one point early on, high levels of soil contaminants become a concern at fields across the region, almost derailing the whole season.

From Los Angeles Times ● May 13, 2026

Midway through this season, though, it looked like things were derailing for Palace.

From BBC ● Apr. 16, 2026

Mining executives, analysts and economic forecasters warn that a copper shortage risks derailing the AI boom, which has fueled stock-market gains and become the main driver of U.S. economic growth.

From The Wall Street Journal ● Jan. 15, 2026

This was the only way to keep Cynthia from disrupting and derailing the entire lesson.

From "Look Both Ways" by Jason Reynolds

Related Words

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