Definition of "gang up on" []

• To join together in a group in order to overpower someone else. (verb)

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• "But Al knew from painful experience that girls'd kick you when you were down and gang up on you whenever they had the chance."
• "The inherited entanglement of the Concert of Europe offered Britain’s Lilliputian rivals the chance to gang up on the British Gulliver, pinning him down with multilateral treaties."