1.NounA 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.; The ice cap of Kilimanjaro is shrinking, and some researchers believe it will disappear within the next one hundred years."
2.NounAn ice pack designed to be worn on the head.