dorm vs dormitory

dorm and dormitory both are nouns.

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

As nouns, dorm and dormitory are synonyms defined as:

dorm and dormitory: a college or university building containing living quarters for students

Other synonyms of dorm include hall, residence hall, student residence.

dorm (noun)	dormitory (noun)
a college or university building containing living quarters for students	a college or university building containing living quarters for students
	a large sleeping room containing several beds