rag week vs rag day

rag week and rag day both are nouns.

Word	Noun	Adjective	Verb	Adverb
rag week	Yes	No	No	No
rag day	Yes	No	No	No

rag week (noun)	rag day (noun)
a week at British universities during which side-shows and processions of floats are organized to raise money for charities	a day on which university students hold a rag