icecap vs ice cap

icecap and ice cap both are nouns.

Word	Noun	Adjective	Verb	Adverb
icecap	Yes	No	No	No
ice cap	Yes	No	No	No

As nouns, icecap and ice cap are synonyms defined as:

icecap and ice cap: a mass of ice and snow that permanently covers a large area of land (e.g., the polar regions or a mountain peak)

icecap (noun)	ice cap (noun)
a mass of ice and snow that permanently covers a large area of land (e.g., the polar regions or a mountain peak)	a mass of ice and snow that permanently covers a large area of land (e.g., the polar regions or a mountain peak)