Synonyms for Gang (same or very similar meaning)
WordNet sense 1 (an informal body of friends):
bunch, crew, crowdWordNet sense 2 (an association of criminals):
mob, pack, ringWordNet sense 3 (an organized group of workmen):
work partyWordNet sense 4 (act as an organized group):
gang upFrom the ODE community, based on WordNetadd/edit