Derail Definition

dē-rāl

derailed, derailing, derails

verb

derailed, derailing, derails

To run or cause to run off the rails.

American Heritage

To come or bring to a sudden halt.

A campaign derailed by lack of funds; a policy that derailed under the new administration.

American Heritage

To go off the rails.

Webster's New World

To cause (a train, etc.) to go off the rails.

Webster's New World

(intransitive) To come off the tracks.

Wiktionary

Synonyms:

noun

A device placed on railway tracks causing a train to derail.

The derail was placed deliberately so that the train would fall into the river.

Wiktionary

Origin of Derail

French dérailler dé- off (from Old French de- de–) rail rail (from English rail¹)

From American Heritage Dictionary of the English Language, 5th Edition
From French dérailler (“to go off the rails”).

From Wiktionary

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