military vs field-grade officer

military and field-grade officer both are nouns.

Word	Noun	Adjective	Verb	Adverb
military	Yes	Yes	No	No
field-grade officer	Yes	No	No	No

military (noun)	field-grade officer (noun)
the military forces of a nation	an officer holding the rank of major or lieutenant colonel or colonel

military (adjective)	field-grade officer (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