ice-cap

Noun

ice cap (plural ice caps)

1. A permanent expanse of ice encompassing a large geographical area, as for example in Earth's polar zones (polar ice) or at high elevation.
   • The ocean beneath the arctic ice cap hosts many unique organisms adapted to the cold and shortage of light.
2. (historical) An ice pack designed to be worn on the head.
   • After the use of ice caps for some days it is well to provide cool bathing for the head, at least three times daily.1903, Canadian Journal of Medicine and Surgery, volume 14, page lii