planes
That could be a plain or a desert.
The flat, wide area along a river is called its flood plain. This is sometimes part of a larger area called the alluvial plain, which formed as the river shifted over time and deposited soil when it flooded.
If you are referring to the crossword puzzle hint, the answer is probably prairie.
The inside of your cranium - vast and completely void of intelligent life.
Plateau.
A plain is a wide area of flat or gently rolling land. Plains cover more than one-third of the world's land area. They exist on every continent.
Plateau.
Plains
its a streem
its a streem
landscape
Mud Slide
planes
The artificial land which is set for cultivating crops in a wide area in our interest.
Alaska by a wide margin followed by Texas.
Sahel