Fantastical describes something so imaginative and unreal that it seems to belong in a fantasy world rather than everyday life. A fantastical creature might have wings, breathe fire, and speak in riddles. A fantastical story might feature magic carpets, talking animals, or cities in the clouds.

The word emphasizes wild imagination and impossibility. While “fantastic” can simply mean “really good,” fantastical specifically points to things that couldn't exist in our ordinary world. The floating islands in Castle in the Sky, the chocolate river in Charlie and the Chocolate Factory, and the wardrobe that leads to Narnia are all fantastical elements.

Writers, artists, and filmmakers create fantastical worlds to explore ideas that realistic stories can't reach. A fantastical setting lets them ask “what if?” in extreme ways: What if animals could talk? What if people could fly? What if time ran backward?

You might describe someone's wild excuse as fantastical when it sounds too elaborate to be true, or call an architect's unusual building design fantastical if it looks like something from a dream. The word suggests something that stretches beyond the boundaries of what's real or believable, into the realm of pure imagination.