A derivative is something created from or based on something else that came before it. When you write a story about a wizard school with four houses and a chosen-one hero, that's derivative of well-known fantasy books: you're borrowing ideas rather than inventing your own. When a movie feels derivative, it means you've seen similar characters, plot twists, and scenes in other movies.

The word often carries a slightly critical tone. While all creative work builds on what came before, calling something derivative suggests it copies too closely without adding enough that's fresh or original. A derivative song might use the same chord progression, melody style, and lyrics as a dozen other hits. A derivative video game might feel like a clone of a more popular game.

In math and science, derivative has a specific technical meaning: it measures how fast something is changing at a particular moment. If you're riding your bike and speeding up, a derivative would tell you your rate of change right now. Scientists use derivatives to track changes in temperature, population growth, or chemical reactions.

The noun form is also used in finance, where a derivative is an investment whose value comes from something else, like the price of gold or wheat.