let-the-cat-out-of-the-bag
/ˌlɛt ðə ˈkæt aʊt əv ðə ˈbæɡ/To accidentally reveal a secret before you were supposed to. The person who does this usually did not mean to say it. It often ruins a surprise or exposes private information.
- She let the cat out of the bag about the surprise party.
- He let the cat out of the bag during the meeting by mistake.
- Don't let the cat out of the bag — it's meant to be a secret!
Adinary Nuance
The idiom's origin is a vivid piece of market trickery: in old English fairs and markets, a seller would promise a piglet but place a cat in the bag instead. The moment a suspicious buyer opened the sack, the fraud was out in the open — you could not put the cat back. This origin explains exactly why the phrase means an irreversible, unplanned reveal: once the cat is out, there is no undoing it. It is directly related to another old English saying, "buy a pig in a poke" (buying something without inspecting it first), both phrases born from the same marketplace con.
In other languages
- Vietnamese
- để lộ bí mật
- Spanish
- irse de la lengua
- Chinese
- 露馅
- Japanese
- 秘密をばらす
- Korean
- 비밀을 드러내다
Etymology
The phrase likely originates from an 18th-century English market fraud, where dishonest traders sold a cat hidden in a sack in place of a more valuable piglet — when the bag was opened, the deception was instantly exposed. Its earliest confirmed printed use in English dates to around 1760.
Common phrases
Synonyms
Related words
Frequently asked questions
- Does 'let the cat out of the bag' always mean an accident?
- Usually yes — the idiom strongly implies an unintentional reveal. However, in casual everyday speech, people sometimes use it even when the disclosure was deliberate, especially in a playful tone.
- What is the difference between 'let the cat out of the bag' and 'spill the beans'?
- Both mean revealing a secret, but 'let the cat out of the bag' puts stronger emphasis on the timing — the secret came out before the right moment, like ruining a surprise. 'Spill the beans' is slightly more casual and can refer to any kind of secret being revealed.
- Can I use 'let the cat out of the bag' in formal writing or business emails?
- It is an informal idiom and sounds conversational, so avoid it in formal reports or professional emails. Use 'inadvertently disclosed' or 'revealed prematurely' for a more formal register.
- Where does the phrase 'let the cat out of the bag' come from?
- It comes from an old English market fraud where sellers hid a cat in a bag instead of a piglet. When a buyer opened the bag to check, the trick was exposed — the cat was literally out of the bag.