脱線(だっせん)

だっせん
noun
derailment, digression
1. derailment
When a train or vehicle leaves the tracks.
電車(でんしゃ)が脱線(だっせん)した。
The train derailed.
脱線(だっせん)事故(じこ)で遅延(ちえん)が発生(はっせい)した。
A derailment accident caused delays.
2. digression, going off topic
Straying from the main subject in a conversation or discussion.
話(はなし)が脱線(だっせん)してしまった。
The conversation went off topic.
すみません、話(はなし)が脱線(だっせん)しましたが、本題(ほんだい)に戻(もど)りましょう。
Sorry, I got off topic, but let's get back to the main subject.
先生(せんせい)の授業(じゅぎょう)はよく脱線(だっせん)するが、その話(はなし)が面白(おもしろ)い。
The teacher often goes off topic in class, but those digressions are interesting.

脱線(だっせん) has both literal (train derailment) and figurative (going off topic) meanings.

COMMON EXPRESSIONS:

USAGE NOTE:
The figurative use is very common in casual conversation when someone strays from the main topic.

[Register: Neutral]

Related Words

Related: 逸脱(いつだつ) (deviation; departure)
general
Added 2026.1.14 9:33 · Revised 2026.6.1 6:07
04500/04514_dassen