oversize vs outsize

oversize is not a noun while outsize is a noun.

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

As adjectives, oversize and outsize are synonyms defined as:

Other synonyms of oversize include outsized, oversized.

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

oversize (adjective)	outsize (adjective)
larger than normal for its kind	larger than normal for its kind