pocket book vs pocketbook

pocket book and pocketbook both are nouns.

Word	Noun	Adjective	Verb	Adverb
pocket book	Yes	No	No	No
pocketbook	Yes	No	No	No

As nouns, pocket book and pocketbook are synonyms defined as:

Other synonyms of pocket book include pocket edition.

pocket book (noun)	pocketbook (noun)
pocket-sized paperback book	a container used for carrying money and small personal items or accessories (especially by women)
	pocket-sized paperback book
	a pocket-size case for holding papers and paper money
	your personal financial means