let the cat out of the bag
verb
Forms lets the cat out of the bag letting the cat out of the bag let the cat out the bag
- verb (idiomatic) To disclose a secret; to let a secret be known, often inadvertently. “It was going to be a surprise party until someone let the cat out of the bag.”
Synonyms
babble blab let the cat out peach sing spill the beans talk tattle babble out blab out
Etymology
First use appears c. 1753 or 1770. The inverse of the idiom pig in a poke. If a dishonest merchant tries to sell a cat as a pig and the cat comes out or is taken out of the bag, the merchant's secret is disclosed.
Sources: Wiktionary · WordNet 3.0 — from the Wiktionary entry “let the cat out of the bag”, CC BY-SA 4.0. Details