Geographical Features:
* Plain: A large, flat area of land, usually without many trees.
* Plateau: A large, flat area of land that is raised above the surrounding land.
* Steppe: A vast, flat, treeless grassland, often found in semi-arid climates.
* Desert: A dry, barren area with little vegetation, often characterized by flat landscapes.
* Mesa: A flat-topped hill with steep sides, often found in desert areas.
* Butte: A smaller, isolated hill with a flat top and steep sides.
Other:
* Level surface: Any surface that is relatively flat and even, such as a table, floor, or road.
* Plane: A flat, two-dimensional surface that extends infinitely in all directions.
To give you a more specific answer, could you tell me what you are looking for?
For example, are you talking about a geographical feature? A physical object? A mathematical concept?