Hill - a landform that extends above the surrounding terrain in a limited area, and often has a distinct summit. Hills may form through a number of geomorhic phenomena: faulting, erosion of larger landforms, such as mountains, and movement and deposition of sediment by glaciers, or by erosion exposing solid rock which then weathers down into a hill.
Butte - an isolated hill with steep sides and a small flat top.
Tor - a rock formation found on a hilltop.
Puy - used especially in Auvergne, France to describe a conical volcanic hill.
Pingo - a mound of earth-covered ice found in the Arctic and also in Antarctica.