Gulf of Mexico vs gulf

Gulf of Mexico and gulf both are nouns.

Word	Noun	Adjective	Verb	Adverb
Gulf of Mexico	Yes	No	No	No
gulf	Yes	No	No	No

Gulf of Mexico (noun)	gulf (noun)
an arm of the Atlantic to the south of the United States and to the east of Mexico	an unbridgeable disparity (as from a failure of understanding)
	a deep wide chasm
	an arm of a sea or ocean partly enclosed by land; larger than a bay