/ˈstuːl ˈpɪdʒən/ – Phrase
Definition: mật báo viên giam chung với tù nhân để khai thác tin tức.
A more thorough explanation: A “stool pigeon” is a person who acts as an informer or decoy, typically providing information to law enforcement authorities in order to catch or incriminate others.
Example: The prosecutor relied on the testimony of a stool pigeon to secure a conviction in the organized crime case.