berserk (adjective) informal 1 ​very angry, often in a violent way or without control: 'He went berserk when he found out where I'd been.' 2 ​very excited: 'People were going berserk with excitement.' go berserk 1 to become very angry, crazy, and violent: 'A worker went berserk and killed his boss.' 2 to become very excited 'The crowd was going berserk as the team scored with seconds to go.'