oversea vs marine

oversea is not a noun while marine is a noun.

Word	Noun	Adjective	Verb	Adverb
oversea	No	Yes	No	Yes
marine	Yes	Yes	No	No

oversea (noun)	marine (noun)
	a soldier who serves both on shipboard and on land

oversea (adjective)	marine (adjective)
being or passing over or across the sea	relating to or characteristic of or occurring on or in the sea
	of or relating to the sea
	of or relating to military personnel who serve both on land and at sea (specifically the U.S. Marine Corps)
	relating to or involving ships or shipping or navigation or seamen
	native to or inhabiting the sea

oversea (adverb)	marine (adverb)
beyond or across the sea