derail

plural derails

1. Synonym of derailer: A device placed on railway tracks in order to cause a train to derail.

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

   Synonyms: derailer

2. An instance of diverting a conversation or debate from its original topic.

present singular third person derails · participle present derailing · participle past derailed · past derailed

1. transitiveTo cause to come off the tracks.

   The train was destroyed when it was derailed by the collision.

   1 more example

   Among recommendations arising out of the accident were that greater attention should be devoted to the means of derailing runaways on lines so heavily graded as the Highland main line; were it double throughout, catch points would, of course, be laid in, but the catchpoint problem is a difficult one on a single line.

   1940 November, “Notes and News: A Highland Collision”, in Railway Magazine, page 612

2. intransitiveTo come off the tracks.

   Fortunately, the CrossCountry train did not derail when it struck the mud. It could easily have been much worse.

   2020 September 9, Paul Clifton, “Heavy rainfall causes landslip in Hampshire: At the scene...”, in Rail, page 10

3. figurativelyintransitiveTo deviate from the previous course or direction.

   The conversation derailed once James brought up politics.

4. figurativelytransitiveTo cause to deviate from a set course or direction.

   The protesting students derailed the professor's lecture.

   1 more example

   Our offices are full of the walking wounded--people who are suicidal, have been hospitalized after the sexual involvement, unable to hold their usual jobs, derailed from intimate relationships, unable to get on with their lives as they once had planned.

   1990 December 23, Nancy Avery et al., “Criminalizing Doctor-Patient Sex”, in Gay Community News, volume 18, number 23, page 5