Meaning

• A terrifying and dangerous creature.

• A bizarre or whimsical creature.

  "The children decided Grover was a cuddly monster."

• A cruel or antisocial person, especially a criminal.

  "Get away from those children, you meatheaded monster!"

• A horribly deformed person.

• A badly behaved child, a brat.

  "Sit still, you little monster!"

• Something unusually large.

  "Have you seen those powerlifters on TV? They're monsters."

• A prodigy; someone very talented in a specific domain.

  "That dude playing guitar is a monster."

• A non-player character that player(s) fight against in role-playing games.

Meaning

• To make into a monster; to categorise as a monster; to demonise.

• To behave as a monster to; to terrorise.

• To harass.

Meaning

• Very large; worthy of a monster.

  "He has a monster appetite."

• Great; very good; excellent.