A nunatak (from Inuitnunataq) is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They are also called glacial islands. Examples are natural pyramidal peaks. When rounded by glacial action, smaller rock promontories may be referred to as rognons.
The word is of Greenlandic origin and has been used in English since the 1870s.