military vs rearguard

military and rearguard both are nouns.

Word	Noun	Adjective	Verb	Adverb
military	Yes	Yes	No	No
rearguard	Yes	No	No	No

military (noun)	rearguard (noun)
the military forces of a nation	a detachment assigned to protect the rear of a (retreating) military body

military (adjective)	rearguard (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