armed vs armed forces

armed is not a noun while armed forces is a noun.

Word	Noun	Adjective	Verb	Adverb
armed	No	Yes	No	No
armed forces	Yes	No	No	No

armed (noun)	armed forces (noun)
	the military forces of a nation

armed (adjective)	armed forces (adjective)
(used of persons or the military) characterized by having or bearing arms
(used of plants and animals) furnished with bristles and thorns
having arms or arms as specified; used especially in combination