Monster meaning : A terrifying and dangerous creature. A bizarre or whimsical creature. A cruel or antisocial person, especially a criminal. A horribly deformed person. A badly behaved child, a brat. Something unusually large. A prodigy; someone very talented in a specific domain. A non-player character that player(s) fight against in role-playing games. To make into a monster; to categorise as a monster; to demonise. To behave as a monster to; to terrorise. To harass. Very large; worthy of a monster. Great; very good; excellent.