Definition of gang-up in US English:

gang-up

noun

informal
  • 1An act of ganging up to oppose or attack someone or something.

  • 2A gathering or group of friends or colleagues; a meeting of a gang.

  • 3Gang-bang. rare.

Origin

1930s; earliest use found in The Chicago Tribune. From gang + up.

Pronunciation

gang-up

/ˈɡaŋʌp/