field day vs armed services

field day and armed services both are nouns.

Word	Noun	Adjective	Verb	Adverb
field day	Yes	No	No	No
armed services	Yes	No	No	No

field day (noun)	armed services (noun)
a day for outdoor athletic competition	the military forces of a nation
a day devoted to an outdoor social gathering
(military) a day for military exercises and display
a time of unusual pleasure and success