rec room vs room

rec room and room both are nouns.

Word	Noun	Adjective	Verb	Adverb
rec room	Yes	No	No	No
room	Yes	No	Yes	No

As nouns, room is a hypernym of rec room; that is, room is a word with a broader meaning than rec room:

rec room (noun)	room (noun)
a room equipped for informal entertaining	an area within a building enclosed by walls and floor and ceiling
	the people who are present in a room
	space for movement
	opportunity for

rec room (verb)	room (verb)
	live and take one's meals at or in