# derailment

/dɪˈɹeɪɫmənt/ (US) · /dɪɹˈeɪlmənt/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/derailment
Updated: 2026-05-30

## Definition

the act of a train coming off its tracks, or a situation that stops a plan from moving forward. It can also describe a person's mind wandering away from the main topic.

For teachers: the act of a train being forced off its rails; by extension, any event that prevents a process or plan from continuing as intended. Often used metaphorically to describe a loss of focus or a deviation from a logical argument.

## Examples

- The heavy snow caused a derailment on the main line.
- A sudden technical failure led to the derailment of the entire project, forcing the team to start over from scratch.
- The speaker's tendency to share personal anecdotes often resulted in a derailment of the central thesis, leaving the audience confused about the original argument.

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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.