high flat terrain

A plateau is an area of raised land that is flat on top.

Mount Roraima in Venezuela is a plateau

The biggest and tallest plateau in the world is the Tibetan Plateau. A plateau with a lot of erosion is called a disconnected plateau. A plateau that is also a volcano is called a volcanic plateau. Some plateaus are under the ocean, like the Seychelles plateau or the Ontong Java Plateau. Plateaus are often by themselves with no other plateaus around, sometimes standing on top of mountains. Plateaus can be of three types: Tectonic Plateaus, Residual Plateaus and Volcanic Plateaus.

The plural of 'plateau' is plateaux, or plateaus.