- violently or destructively frenzied; wild; crazed; deranged: He suddenly went berserk.
- an ancient Norse warrior who fought with frenzied rage in battle, possibly induced by eating hallucinogenic mushrooms.
- frenziedly violent or destructive (esp in the phrase go berserk)
- a member of a class of ancient Norse warriors who worked themselves into a frenzy before battle and fought with insane fury and courage
