It is called a plain.
The opposite of the adjective "flattest" is "steepest."
The Earth's flattest regions are commonly referred to as "plains." Plains are extensive areas of flat or gently rolling land, often characterized by fertile soil and minimal elevation changes. They can be found on every continent and are typically important for agriculture and settlement due to their accessibility and productivity. Examples include the Great Plains in North America and the Pampas in Argentina.
continental air masses
land slides form when the ground gets too soft from water (ex. rain.)
The wide and flat land form that repeated flows of lava form is called a lava plateau. Lava plateaus are created by successive eruptions of low-viscosity lava that spreads out in thin layers, building up over time to create a broad, flat area.
Plains are the flattest kind of land form, typically characterized by low elevation, minimal slope, and a fairly uniform surface. They cover extensive areas of land and are often found in regions like the central United States and parts of Russia.
flattest
I can give you several sentences.This is the flattest land I've ever seen.You need to see who can make the flattest piece of paper in art class.I think that must be the flattest tire in the world.
Coastal Plain
The flattest country in the world is Maldives.
No;it is just the flattest.
Middle Tennessee
Yes. The adjective "flattest" is the superlative form of the adjective flat. The comparative form also doubles the final T (flatter) which is the same spelling as the verb flatter.
Flattest.
The southern coast along the Gulf of Ghana and around Lake Volta
flatter/flattest
It is called a plain.