smell a rat

S

smell a rat (idiom)
/ˈsmɛl ə ræt/

Meaning

• Suspect something is wrong or dishonest.
• Feel that someone is lying or hiding the truth.
• Sense a hidden trick, betrayal, or setup.
• Detect deceit or corruption in a situation.
• Feel suspicious without clear proof.

Synonyms: suspect; doubt; distrust; sense; detect

Example Sentences

1. I smell a rat—he’s being too nice all of a sudden.
2. When the numbers didn’t add up, the auditor smelled a rat.
3. She smelled a rat when her friend canceled dinner for the third time.
4. The police smelled a rat in his alibi and investigated further.
5. Investors smelled a rat in the company’s sudden growth.

Origin and History

The Feline Instinct

One of the most widely accepted theories suggests that the idiom comes from the natural behavior of cats. Cats are known for their exceptional sense of smell, which they use to hunt prey. When a cat smells a rat, it knows the rodent is nearby, even if it can’t see it. This gives the cat a strong sense that something is amiss or that a hidden presence is nearby. The idea is that just as a cat can detect a hidden rat by its scent, a person can intuitively sense a hidden problem, deception, or danger, even if they don’t have clear evidence. This theory highlights the instinctual recognition of a concealed threat.

The Canine Connection

Another theory proposes that the phrase relates to the behavior of terriers, a type of dog specifically bred to hunt rats and other vermin. These dogs have a highly developed sense of smell and would “scent mischief” or the presence of rats without necessarily seeing them. This theory suggests that the phrase alludes to the dog’s ability to detect its prey, even when hidden, thus linking the idiom to the detection of a hidden issue or a sly person.

The Unpleasant Odor

A more direct, albeit less complex, theory points to the literal smell of rats. Rats, particularly dead ones, can produce a strong and unpleasant odor. If someone smells a rat in a literal sense, it means there’s a rat present, often in a hidden or inconvenient place like behind a wall or under floorboards. This theory suggests that the idiom arose from the literal experience of detecting a foul smell that indicates a hidden problem, much like a metaphorical “foul smell” indicating something untrustworthy.

A Mistranslation Theory

There is also a theory that the phrase might have originated from a mistranslation of an old German saying:“unrath wittern,” which roughly means “to scent mischief.” This was supposedly changed to “eine ratte wittern,” meaning “I smell a rat.” While intriguing, this theory is less commonly supported than those rooted in animal behavior.

Country of Origin

The phrase “smell a rat” appears to have originated in England. Its earliest recorded instances are found in English literature, pointing to its development within the English language.

Earliest Printed Record

One of the earliest printed records of the term appears in the English playwright Ben Jonson’s play, The Case Is Altered, which was first performed in December 1599. In the play, a character named Babulo exclaims:

“Whoop! Whither is my brother basket-maker gone? Ha! Let me see: I smell a rat.”

The phrase also appears in Samuel Butler’s Hudibras, with Book Two published in 1664, containing the line:

“Quoth Ralpho, who could hold no longer, / Although I am no good States-Monger, / Yet I begin to smell a Rat, / And what your Worship would be at.”

These early appearances indicate that the idiom was already in use in English speech and writing by the late 16th and mid-17th centuries, solidifying its English origins.

Variant

• smell fishy

Animal

Last update: July 28, 2025 8:29 AM