big vs outsize

big is not a noun while outsize is a noun.

Word	Noun	Adjective	Verb	Adverb
big	No	Yes	No	Yes
outsize	Yes	Yes	No	No

big (noun)	outsize (noun)
	an unusual garment size (especially one that is very large)

big (adjective)	outsize (adjective)
above average in size or number or quantity or magnitude or extent	larger than normal for its kind
conspicuous in position or importance
given or giving freely
generous and understanding and tolerant
marked by intense physical force
significant
prodigious
serious or severe
loud and firm
(of animals) fully developed
in an advanced stage of pregnancy
feeling self-importance
exhibiting self-importance