An ice body originating on land that covers an area of continental size, generally defined as covering >50,000 km², and that has formed over thousands of years through accumulation and compaction of snow. An ice sheet flows outward from a high central ice plateau with a small average surface slope. The margins usually slope more steeply, and most ice is discharged through fast-flowing ice streams or outlet glaciers, often into the sea or into ice shelves floating on the sea. There are only two ice sheets in the modern world, one on Greenland and one on Antarctica. The latter is divided into the East Antarctic Ice Sheet , the West Antarctic Ice Sheet  and the Antarctic Peninsula Ice Sheet. During glacial periods, there were other ice sheets.
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report