Chickasaw National Recreation Area vs OK

Chickasaw National Recreation Area and OK both are nouns.

Word	Noun	Adjective	Verb	Adverb
Chickasaw National Recreation Area	Yes	No	No	No
OK	Yes	No	No	Yes

Chickasaw National Recreation Area (noun)	OK (noun)
a national park in Oklahoma having mineral springs	an endorsement
	a state in south central United States

Chickasaw National Recreation Area (adverb)	OK (adverb)
	an expression of agreement normally occurring at the beginning of a sentence