dorm room vs dormitory room

dorm room and dormitory room both are nouns.

Word	Noun	Adjective	Verb	Adverb
dorm room	Yes	No	No	No
dormitory room	Yes	No	No	No

As nouns, dorm room and dormitory room are synonyms defined as:

dorm room and dormitory room: a large sleeping room containing several beds

Other synonyms of dorm room include dormitory.

dorm room (noun)	dormitory room (noun)
a large sleeping room containing several beds	a large sleeping room containing several beds