Kinktionary
More like guidelines and a lot less like definitions.
Blowbang
A version of a gangbang where the people in focus will only perform blowjobs on participants. The group of participants is at least 4 people, but can also be a lot larger than that. There is likely a single person being focused on as the receiver of a blowjob, but with larger groups more people can be focused on as the receiver. Gangbangs tend to have more options for people to participate in at the same time while focusing on a single person than blowbangs do.
Often this is combined with facials from the different participants.