Zenith means the highest point or peak of something. When the sun reaches its zenith at noon, it's directly overhead at its highest position in the sky. When a basketball player's career reaches its zenith, they're performing at their absolute best, like Michael Jordan during his championship years with the Chicago Bulls.

The word comes from astronomy, where the zenith is the point in the sky directly above an observer's head. Ancient astronomers used this concept to map the heavens and navigate by the stars. If you lie on your back and look straight up, you're looking at your zenith.

Today we use zenith to describe any peak moment or maximum achievement. A company might reach the zenith of its success. A civilization at its zenith is at its most powerful and influential. The Roman Empire reached its zenith under Emperor Trajan, controlling more territory than at any other time in its history.

The opposite of zenith is nadir, which means the lowest point. If zenith is standing on a mountain peak with your arms raised in victory, nadir is being down in the deepest valley. Understanding both words helps you describe the full range of human experience, from your greatest triumphs to your toughest challenges.