luːs ˈkænən
General
informal
intermediate
- Literally:
- A cannon that has become unfastened
What does "loose cannon" mean?
- An unpredictable person who may cause unintentional damage
- Someone whose behavior is hard to control
Examples
- He's a loose cannon who might say anything to the press.
- We can't have a loose cannon on the team.
- She's brilliant but a bit of a loose cannon.
Origin
From naval warfare—cannons on ships were tied down. A loose cannon rolling on deck in rough seas was extremely dangerous to the crew.
How to use it
Usually describes people in positions of responsibility. Implies potential for harm.
Similar expressions
unpredictable
wild card
liability
hothead
Opposites
reliable
dependable
steady
predictable
Related idioms
- actions speak louder than words
What people do is more important than what they say
- better safe than sorry
It's better to be careful and prevent problems than to take risks
- so far so good
Things have gone well up to now
- easier said than done
Something is more difficult to do than to talk about
- make a long story short
To summarize or get to the point
- to make matters worse
In addition to existing problems
Use it in a practice answer
Try "loose cannon" in a CELPIP-style Speaking or Writing task. The AI feedback tells you whether your word choice worked.