Wicked means morally bad or evil, done with the intention to harm others or do wrong. A wicked villain in a story schemes to hurt innocent people. A wicked deed is one that causes suffering on purpose. The word suggests deliberate, serious wrongdoing: it implies a conscious choice to do harm or act against what's right.

In fairy tales, wicked stepmothers and wicked witches plot against the heroes. In real life, we might call someone's cruel behavior wicked if they intentionally hurt others without remorse. A wicked lie is one designed to damage someone's reputation or cause real trouble.

Interestingly, the word has picked up an opposite slang meaning in some places, where people say “wicked” to mean extremely good or impressive. In parts of New England, someone might say “That's wicked cool!” to mean something is really awesome. But in most contexts, especially in books and formal writing, wicked still carries its original meaning of evil or morally wrong.