loose cannon
Plural
loose cannons
1
a person who has lost their sanity, often momentarily
The idiom "loose cannon" originated from nautical terminology. In the era of sailing ships, a "loose cannon" referred to a cannon that had broken free from its moorings during naval battles. It is used to describe a person who is unpredictable, impulsive, and not under control, often acting in a way that can cause harm or problems.
- Don't rely on him for critical tasks; he's proven to be a loose cannon with his unreliable actions.
- The new employee's aggressive behavior is like a loose cannon in the office, causing tension among the team.
- The politician's controversial statements are making him appear as a loose cannon, causing his party to worry about public perception.
- We need to be cautious around Tom; he's a loose cannon and could jeopardize the entire project with his impulsive decisions.