From French dérailler (“to go off the rails”). Analyzable as de- + rail.
Meanings
(transitive) To cause to come off the tracks.
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:
The train was destroyed when it was derailed by the collision.
(intransitive) To 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:
(figuratively, intransitive) To deviate from the previous course or direction.
The conversation derailed once James brought up politics.
(figuratively, transitive) To cause to deviate from a set course or direction.
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:
The protesting students derailed the professor's lecture.
es desrielar (to cause to come off the tracks) · hu kisiklik (to cause to come off the tracks) · ru сорва́ть (to cause to deviate from a set course or direction) · cy direilio (to cause to come off the tracks) · el εκτροχιάζομαι (to cause to come off the tracks) · ru пуска́ть под отко́с (to cause to deviate from a set course or direction) · fi suistaa (to cause to deviate from a set course or direction) · ro submina (to cause to deviate from a set course or direction) · no spore av (to cause to come off the tracks) · vi trật bánh (to cause to come off the tracks) · fi suistua raiteilta (to cause to come off the tracks) · pt descarrilar (to cause to come off the tracks) · pl wykolejać się (to cause to come off the tracks) · cmn 出軌 /出轨 (to cause to come off the tracks) · fr dérailler (to deviate from the previous course or direction) · cs vykolejit (to cause to come off the tracks) · cmn 脫軌 /脱轨 (to cause to come off the tracks) · pl wykoleić się (to cause to come off the tracks) · sv spåra ur (to cause to come off the tracks) · hu kisiklat (to cause to deviate from a set course or direction) · de entgleisen (to deviate from the previous course or direction) · it deragliare (to cause to come off the tracks) · fi suistua (to deviate from the previous course or direction) · es descarrilar (to cause to come off the tracks) · it sbandare (to deviate from the previous course or direction) · fr dérailler (to cause to come off the tracks) · ro deraia (to cause to come off the tracks) · la dēlīrō (to deviate from the previous course or direction) · ca descarrilar (to cause to come off the tracks) · fi suistua raiteilta (to deviate from the previous course or direction) · pt descarrilhar (to cause to come off the tracks) · de entgleisen (to cause to come off the tracks) · es descarriar (to cause to come off the tracks) · fi suistaa raiteilta (to cause to deviate from a set course or direction) · cmn 越軌 /越轨 (to cause to come off the tracks) · it deragliare (to deviate from the previous course or direction) · ru сходи́ть с ре́льсов (to cause to come off the tracks) · de zum Entgleisen bringen (to cause to deviate from a set course or direction) · ml പാളം തെറ്റുക (to cause to come off the tracks) · ru срыва́ть (to cause to deviate from a set course or direction) · ru сойти́ с ре́льсов (to cause to come off the tracks) · bg дерайлирам (to cause to come off the tracks) · nl ontsporen (to cause to come off the tracks)