Berserk/bərˈzɜːrk,bərˈsɜːrk/ Definition 1 of 3Pro Tip 1/3Extreme Reaction Use 'berserk' to describe a very extreme and often violent reaction to something. She went berserk when her favorite vase was shattered. Pro Tip 2/3Informal Tone 'Berserk' is common in casual, conversational settings rather than formal writing. If my brother eats my cake, I'll go berserk! Pro Tip 3/3Negative Implication 'Berserk' implies a loss of control and is usually seen in a negative light. The manager went berserk during the meeting, which was unsettling.