What is the difference between a monadnock, an inselberg and a monocline?

An inselberg is an isolated hill, ridge, or small mountain that abruptly protrudes out from a virtually level surrounding plain. The word inselberg translates to "Island Mountain" in German, and it was first used by Wilhelm Bornhardt in 1900, a geologist who found the landforms in southern Africa. The word monadnock is of Native American origin and it refers to a solitary hill rising above the flat area surrounding it.

Monocline
A one-sided fold-like structure in which layers of rock warp upwards or downwards.