Villainous means evil, wicked, or characteristic of a villain. A villainous plot is a scheme designed to hurt people or steal something valuable. A villainous character in a story does cruel or dishonest things without caring about the harm they cause.

In classic stories, villainous characters like the wicked stepmother in Cinderella or Scar in The Lion King use deception and cruelty to get what they want. What makes someone villainous is a pattern of selfish, harmful behavior without remorse.

You might describe a truly nasty practical joke as villainous, though this use is exaggerated and playful. When something is genuinely villainous, though, it's seriously wrong: a villainous act might involve betraying someone's trust in a devastating way or deliberately hurting innocent people for personal gain.

The opposite of villainous would be heroic or noble: acting with courage and kindness rather than cruelty and selfishness.