A plateau is a large, flat area of land that sits high above the surrounding landscape, like a tabletop mountain. While plateaus are flat on top, their sides drop steeply down to lower ground. The Colorado Plateau in the American Southwest stretches across four states and rises thousands of feet above the desert floor. Some plateaus form when underground forces push rock layers upward, while others form when rivers and wind erode softer rock around harder layers, leaving the flat tops behind.

The word also describes a period when progress or improvement stops, even though you're still working hard. If you practice piano every day and steadily improve, but then your skills seem stuck at the same level for weeks, you've hit a plateau. Athletes plateau when their performance stops improving despite continued training. Scientists studying a problem might find their progress plateaus when they've learned everything their current methods can teach them.

The key to both meanings is flatness: geographic plateaus are physically flat, while progress plateaus feel flat because nothing's changing. When you plateau in your learning, it doesn't necessarily mean you're doing anything wrong. Sometimes your brain needs time to absorb what you've learned before the next breakthrough comes.