intransitive verb
Etymology: gang (II) + up
1. : to combine for a specific purpose
sellers gang up to raise prices — Picture Post
ganged up to kill the bill
: attack or oppose someone or something as a group — often used with on or against
planning to gang up on us and push us around — Dorothy C. Fisher
ganged up on him one night and beat him up
all ganged up against each power that in succession became strongest — Elmer Davis
the whole world ganged up against Britain — H.L.Matthews
2. : to take sides
gave … an impression of ganging up with her against me — Nigel Balchin