Nosedive means to drop suddenly and steeply, nose-first. The word originally described what happens when an airplane points its nose downward and plunges toward the ground. A pilot might put a plane into a controlled nosedive during an air show stunt, or a plane might go into an uncontrolled nosedive if something goes wrong.

You can picture it: the front end goes down first, like when you dive into a pool. But unlike a graceful dive, a nosedive suggests speed, suddenness, and often trouble.

The word also describes anything that drops or declines sharply. If your grades take a nosedive, they fall quickly from good to poor. A company's stock price might nosedive after bad news. Your mood could nosedive when you discover you forgot your lunch at home. A basketball team's championship hopes might nosedive after their star player gets injured.

When something nosedives, the drop is dramatic and noticeable. A small dip isn't a nosedive. But when things go from great to terrible in a short time, when the decline is steep and obvious, that's a nosedive. The word captures both the direction (downward) and the speed (fast) of the fall.