Behind someone's back Informal

English idiom: Behind someone's back

Last updated: 14.09.2026

Equivalent idioms in other languages

Meaning

Doing, saying, or deciding something without a person’s knowledge or consent, especially when it concerns them directly and they would likely object if they knew.

It often carries a negative, disapproving tone, implying disloyalty, dishonesty, or a betrayal of trust, such as gossiping about someone or making decisions that affect them without consulting them.

Origin

The phrase draws on the simple physical fact that a person’s back is the one part of their body from which they cannot see what is happening; anything done there, literally out of their field of vision, happens without their awareness. This physical image of being unable to see becomes a natural metaphor for being kept unaware or deceived, especially when the concealment is deliberate.

Examples

She found out that her colleagues had been complaining about her behind her back.

He signed the papers behind his business partner’s back, without ever mentioning it.

It is disrespectful to criticize someone behind their back instead of talking to them directly.

A: Did you hear they changed the schedule without telling him?

B: Yes, they did it completely behind his back.

Frequently asked questions

What does 'Behind someone's back' mean?

Doing, saying, or deciding something without a person’s knowledge or consent, especially when it concerns them directly and they would likely object if they knew.

It often carries a negative, disapproving tone, implying disloyalty, dishonesty, or a betrayal of trust, such as gossiping about someone or making decisions that affect them without consulting them.

How do you say 'Behind someone's back' in Russian?

За спиной

How do you say 'Behind someone's back' in Spanish?

A espaldas de alguien

How do you say 'Behind someone's back' in French?

Dans le dos de quelqu'un

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