Smell a rat

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The phrase to smell a rat is an idiom that dates back to the 1500s. We will examine the meaning of the phrase to smell a rat, where it came from and some examples of its use in sentences.

To smell a rat means to become suspicious that something in a given situation is not quite right, to believe that someone is attempting to trick you or that the circumstances are not quite what they seem to be. Usually, the phrase is rendered in the expression I smell a rat, or Do you smell a rat? The phrase comes from the very literal fact that rats smell. Rats are an indigenous species on every continent except Antarctica. Two of the main species of rat or rattus are the black rat, also known as a house rat, roof rat or ship rat, and the brown rat, also known as a wharf rat, Norwegian rat, Norway rat, common rat, sewer rat, street rat or Parisian rat. Wild rats are found in garbage dumps, garbage cans, sewer pipes, warehouses, subways and ships’ holds, but they are also found in houses. Anywhere there is a food source, rats and mice and other rodents may be found. Rats will go to great lengths to find food, foraging in your basement, crawl space, attic, walls, and anyplace with access holes. Pet food is a popular feeding place for these omnivore rodents, known to gnaw into boards or walls and crawl into very secure spaces. Many people are aware that rats carry the bubonic plague from fleas breeding on them, but plague is only one of many diseases that this pest carries. Leptospirosis, typhus, hantavirus, salmonella and streptococcus are all diseases that are spread by rats. Many methods of rodent control are practiced around the world, including traps with bait, or the use of a rodenticide or poison. The idiom smell a rat dates back to one of the oldest methods of controlling the rat population–a cat. The idiom to smell a rat is a reference to a cat’s sense of smell. The earliest uses of this phrase involves not only a rat, but a cat. For instance, The Image of Ipocrysy, a poem written in 1540 and attributed to John Skelton, though he probably did not write it: “But then beware the catte; For yf they smell a ratt, They grisely chide and chatt…” Note that in this examples it is a cat that is smelling the rat. Eventually, the idiom simply became to smell a rat, dropping the reference to the cat. Related terms are smells a rat, smelled a rat, smelling a rat.


The woman wondered where everyone’s tax money goes: “I suspect that I smell a rat,” she said. (The Minneapolis Star Tribune)

Quickly though, people began to smell a rat, suggesting that the men in the video knew each other and the clip was staged. ‏ (The Daily Mail)

One would believe our economies would be reducing our dependence on debt, not increasing debt as appears the case, so I smell a rat in our present system, not in our best interests. (The New Zealand Herald)

Some Hamilton City Councillors smell a rat in allegations made against city chief Richard Briggs. (The Waikato Times)