# derail

/dɪˈɹeɪɫ/ (US) · /dɪɹˈeɪl/ (UK)

Source: https://englishreference.com/word/derail
Updated: 2026-08-27

## Senses

### 1. train coming off tracks

verb · CEFR B2

to come off the tracks, or to cause a train to do so.

For teachers: to cause a locomotive or train to leave the rails; also used intransitively for the event itself.

- The heavy snow managed to derail the freight train just outside the city.
- Investigators are still trying to determine whether the faulty switch was enough to derail the locomotive at such a low speed.

Usage: Used both transitively (something derails the train) and intransitively (the train derails).

### 2. to ruin a plan

verb · CEFR B2

to stop a process or plan from working by causing a sudden problem.

For teachers: to obstruct or divert a process, plan, or project from its intended course.

- A sudden lack of funding threatened to derail the entire research project.
- The scandal threatened to derail the senator's re-election campaign just weeks before the final vote.

### 3. to divert a conversation

verb · CEFR C1 · Informal

to change the subject of a discussion so that the original point is ignored.

For teachers: to divert a conversation or debate from its original topic, often intentionally.

- He tried to derail the meeting by bringing up old arguments about the budget.
- The moderator struggled to keep the debate on track as the candidates repeatedly tried to derail the discussion with personal attacks.

### 4. a disruption

noun · CEFR C1 · Academic

an instance where a conversation or plan is pushed off its path.

For teachers: the act or an instance of diverting a process or discussion from its intended goal.

- The sudden derail of the peace talks surprised the international community.
- The committee noted that the derail of the original proposal was due to a lack of clear communication between departments.

## Examples

- A small mistake could derail the whole project.
- The sudden resignation of the lead architect threatened to derail the construction schedule for the new hospital wing.
- While the literal sense involves a train leaving its rails, the term is more frequently used to describe how unforeseen political scandals can derail even the most carefully managed legislative agendas.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.