Astonished means extremely surprised, so much so that you're momentarily stunned or amazed. When you're astonished, something catches you so off guard that you might stop in your tracks, your eyes widen, or your mouth falls open.

Imagine walking into your classroom and discovering that your teacher has completely transformed it into a rainforest, with vines hanging from the ceiling and tropical bird sounds playing. That feeling of total shock and wonder is astonishment. Or picture opening a gift you never expected and finding exactly what you'd been dreaming about for months. You'd be astonished.

The word suggests more than simple surprise. Being startled by a sudden noise is different from being astonished. Astonishment combines surprise with wonder or disbelief. People were astonished when they learned that the Earth orbits the Sun, not the other way around. A magician astonishes an audience by doing something that seems impossible.

You might say “I was astonished to learn that octopuses have three hearts” or “The audience watched in astonishment as the gymnast completed a perfect routine.” The feeling is powerful but temporary: that breathless moment when reality exceeds what you thought was possible.