military vs brass hat

military and brass hat both are nouns.

Word	Noun	Adjective	Verb	Adverb
military	Yes	Yes	No	No
brass hat	Yes	No	No	No

military (noun)	brass hat (noun)
the military forces of a nation	a high-ranking military officer

military (adjective)	brass hat (adjective)
associated with or performed by members of the armed services as contrasted with civilians
characteristic of or associated with soldiers or the military
of or relating to the study of the principles of warfare