An apex is the highest point or peak of something. When you climb to the apex of a mountain, you've reached the very top. The apex of a triangle is the corner point opposite the base.

The word often describes moments of greatest achievement or intensity. An athlete might reach the apex of their career when they win an Olympic gold medal. A rocket reaches its apex when it stops climbing and begins to fall back toward Earth. In nature, eagles soar to the apex of their flight before diving down to catch prey.

You'll also hear apex used to describe something that's the ultimate example of its kind. An apex predator is an animal at the top of the food chain with no natural predators, like a great white shark or a polar bear. These creatures represent the apex of hunting ability in their ecosystems.

When you use apex, you're usually emphasizing that nothing goes higher: whether it's a physical peak, a moment of success, or a position of power, the apex is as high as it gets.