Blow someone’s cover

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To blow someone’s cover is an idiom that has been in use for about one hundred years. We will examine the definition of the phrase blow someone’s cover, where it came from and some examples of its use in sentences.

To blow someone’s cover means to expose someone’s true identity, to expose someone’s true purpose, to reveal someone’s true, hidden motives. The term blow someone’s cover is related to the word undercover, which means to operate in secret, usually with a fake identity. Policemen may work undercover in order to infiltrate criminal organizations. Journalists may work undercover in order to expose corruption. Spies may work undercover in order to gather intelligence. If the true identity of such a person is exposed, then someone has blown their cover. This may result in someone being put in danger, or it may simply foil that person’s plans. Sometimes the term blow someone’s cover is used in a humorous way, to mean spoiling a surprise. Related terms are blows someone’s cover, blew someone’s cover, has blown someone’s cover, blowing someone’s cover.


“She escorted me to a silver trailer and knocked on the door, whereupon two stylists answered and yanked me inside as if I were a spy about to blow my cover.” (The Minneapolis Star Tribune)

Police are closing in on a burglary suspect who broke into a home in south Arlington last week and blew his cover when he tried to deactivate the home surveillance video camera. (The Fort Worth Star Telegram)

The enemy might spot your agents, seemingly by chance, blowing your cover and exposing your team to an inevitably dismal firefight. (The Guardian)

He admitted it was the first moment he had a “physical reaction” to something a target said, and he “saw red” and worried he had blown his cover. (The Sun)