介入

1. Origins, structure, and basic meaning

• Structure: 介入 is a noun and irregular intransitive verb read かいにゅう, meaning intervention by a third party in an ongoing matter or conflict.
• Basic usage: Mark the matter entered with に, as in 口論に介入する, and use 介入しすぎる for excessive intervention.
  • 二人の口論に第三者が介入して、話を整理しました。 describes a third party intervening in an argument and organizing the discussion; 親が細かく介入しすぎると、子どもが自分で決めにくくなります。 says that excessive parental intervention can make it difficult for a child to decide independently.

2. Common pitfalls and similar expressions

• 口論に介入する
  • に marks the event or situation into which the third party intervenes.
• 介入しすぎると
  • すぎる shows that intervention exceeds an appropriate degree, and と introduces the resulting general consequence.
• 介入 and 参加
  • 参加 focuses on joining an activity as a participant, while 介入 more strongly suggests entering an ongoing matter and affecting it.