A monadnock or inselberg is an isolated hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In southern and southern-central Africa, a similar formation of granite is known as a kopje from the Afrikaans word: koppie. In fact the word koppie is itself frequently employed in written South African English.
Monadnock is an originally Native American term for an isolated hill or a lone mountain that has risen above the surrounding area, typically by surviving erosion. The name was taken from Mount Monadnock in southwestern New Hampshire (USA), in Jaffrey. The name is thought to derive from the Abenaki language, from either menonadenak ("smooth mountain") or menadena ("isolated mountain").
The word inselberg is German for "island mountain"; the name was originally coined to describe the abundant such features found in southern Africa. The term monadnock is more usually used in the US.