Impromptu means done without planning or preparation. When you give an impromptu speech, you stand up and talk without having written anything down ahead of time. When friends drop by for an impromptu visit, they show up at your door unannounced.

A skilled musician can give an impromptu performance, making up melodies on the spot. A quick-thinking student might deliver an impromptu answer in class that sounds thoughtful and complete, even though they just thought of it seconds ago.

Impromptu moments often feel exciting because they're spontaneous and unrehearsed. An impromptu snowball fight breaks out when the first snow falls. An impromptu party happens when a small gathering of friends suddenly turns into something bigger and more fun. These unplanned moments can become some of the most memorable ones.