Definition of gangbang in US English:
 gangbang
nounˈɡaNGˌbaNGˈɡæŋˌbæŋˈɡæŋˌbæŋ
informal 1The successive rape of one person by a group of people.
 Synonyms
sexual assault, sexual abuse
- 1.1 A sexual orgy involving changes of partner.
 Synonyms
wild party, debauch, carousal, carouse, revel, revelry, bacchanalia, bacchanal, saturnalia, dionysiacs
 
2North American An instance of violence involving members of a criminal gang.
verbˈɡaNGˌbaNGˈɡæŋˌbæŋˈɡæŋˌbæŋ
informal 1with object (of a group of people) rape (someone).
 Synonyms
sexually assault, violate, force oneself on, abuse sexually
2as noun gangbangingNorth American The violent activities of a criminal gang.