Unprecedented means something that has never happened before, with no earlier example to compare it to. When scientists discover an unprecedented species of deep-sea creature, they mean nothing like it has ever been found. When a basketball player scores an unprecedented 100 points in a single game (as Wilt Chamberlain did in 1962), no player had ever reached that mark before.

Courts use precedents from past cases to help decide new ones. When something is unprecedented, there's no earlier case to look back on, no roadmap to follow.

You might hear about unprecedented weather, like record-breaking temperatures, or unprecedented achievements in science or sports. During unusual times, people often describe events as unprecedented to emphasize how strange or remarkable they are. A teacher might say a student's science project was unprecedented in its creativity, meaning nothing quite like it had been done before in that class.

The word carries a sense of surprise or significance. We don't usually call ordinary, everyday things unprecedented. We reserve it for moments when something truly breaks new ground.