Smell a rat
/smel ə ræt/informalUK · US
What does “Smell a rat” mean?
Smell a rat means to suspect that something dishonest is happening
A seller who demands payment but refuses to show the item might make you smell a rat. Something about the story does not feel right.
It is stronger than simply being confused. The speaker suspects that someone is hiding or misrepresenting something.
When do people say it?
Use it when a detail makes you suspect a trick or hidden problem. It expresses suspicion, not proof.
“I smelled a rat when the seller refused to show me the bicycle.”
Is it formal or informal?
Register: informal. It is most at home in everyday conversation rather than formal writing. Most common in UK and US.
Where does it come from?
The image is of detecting something hidden by its smell. In the idiom, the hidden thing is a trick or a dishonest plan rather than a rat.
Origin confidence: Disputed; treat with caution
How do you say “Smell a rat” in other languages?
Last updated 2026-10-01