an act of ganging up or uniting in opposition to someone or something.
Origin
1935-40; noun use of verb phrase gang up (on)
British Dictionary definitions for gang up
gang up
verb
1.
(informal) often foll by on or against. to combine in a group (against)
Idioms and Phrases with gang up
gang up
.
Also, gang up with. Act together as a group. For example, The residents ganged up to make the neighborhood safer. [ ; c. 1920 ]
.
gang up on or against. Join in opposition or attack against, as in The big kids were always ganging up on the little ones, or They all ganged up against the substitute teacher. [ 1920s ]