derail

verb

de·​rail di-ˈrāl 

dē-

derailed; derailing; derails

transitive verb

1

: to cause to run off the rails

2

a

: to obstruct the progress of : frustrate

Security problems derailed the tour.

b

: to upset the stability or composure of

… divorce … can seriously derail an employee.

—Joanne Gordon

intransitive verb

: to leave the rails

derailment

di-ˈrāl-mənt 

dē-

noun

Synonyms of derail

• distract
• disturb
• bother
• worry
• alarm
• concern
• unsettle
• agitate
• anger

Examples of derail in a Sentence

The train derailed in heavy snow.

The train was derailed by heavy snow.

Recent Examples on the Web

Willis was questioned about her selection of Nathan Wade as a special prosecutor, a decision which ultimately derailed the prosecution of the RICO case after it was revealed that Willis and Wade had a romantic relationship. —Jack Birle, The Washington Examiner, 17 Dec. 2025

While no one was on the train that derailed, the main line was affected, and thus, Yellow Line services had to be suspended while Chicago Transit Authority workers rerailed the train. —Adam Harrington, CBS News, 16 Dec. 2025

Unfortunately, this isn't the first time an animal has stowed away on a flight and derailed travel plans. —Marina Watts, PEOPLE, 15 Dec. 2025

Akio Maeshima | Digitalvision | Getty Images Year-end financial planning is tricky — and surprise portfolio income can derail your tax strategy, experts say. —Kate Dore, Cfp®, Ea, CNBC, 15 Dec. 2025

Word History

Etymology

French dérailler to throw off the track, from dé- de- + rail, from English

First Known Use

1850, in the meaning defined at transitive sense 1

Rhymes for derail

• airmail
• assail
• avail
• bewail
• blackmail
• cattail
• cocktail
• curtail
• detail
• dovetail
• email
• entail

Kids Definition

derail

verb

de·​rail di-ˈrā(ə)l 

: to cause to run off the rails

a train derailed by heavy snow

derailment

-mənt 

noun