rag day vs rag week

rag day and rag week both are nouns.

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

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