What does 脱線 mean?
脱線 is a Japanese noun meaning “derailment, digression” in English. It can also be translated as “digression” depending on context. It is written as 脱線 in kanji, だっせん in hiragana, and dassen in romaji. This word is part of JLPT N2 vocabulary.
Example sentence
脱線がどんどんエスカレートしていく。
The digression is escalating more and more.