Mesa

A mesa is an elevated area of land with a flat top and surrounded on all sides by steep cliffs. It takes its name from its characteristic table-top shape (mesa = "table" in Spanish)

It is a characteristic landform of arid environments, particularly the south-western United States and is generally formed when land has been uplifted by tectonic activity and then exposed to wind erosion.

A mesa is similar to, but smaller than a plateau, and similar to, but larger than a butte.

Also, an open source programming library.