A glacial body covering less than 50,000 square kilometers is generally called an ice cap. Ice caps are dome-shaped masses of ice that spread outward over land and are smaller than ice sheets by the standard area-based distinction.
An ice cap can bury the underlying landscape, but its ice usually flows outward in multiple directions and may feed outlet glaciers along its margins. Iceland contains several major ice caps, including Vatnajökull, while the much larger Greenland and Antarctic ice masses are classified as ice sheets.
The area threshold helps distinguish an ice cap from an ice sheet, but it does not describe an iceberg or an ice shelf. An iceberg is floating ice that has calved from a glacier or ice shelf. An ice shelf is a floating extension of land-based ice attached to a coast. The phrase polar ice cap can be used more broadly for icy polar regions, including sea ice, so context matters when interpreting the term.