nicknack vs knickknack

nicknack and knickknack both are nouns.

Word	Noun	Adjective	Verb	Adverb
nicknack	Yes	No	No	No
knickknack	Yes	No	No	No

As nouns, nicknack and knickknack are synonyms defined as:

Other synonyms of nicknack include bric-a-brac, knickknackery, whatnot.

nicknack (noun)	knickknack (noun)
miscellaneous curios	miscellaneous curios
	a small inexpensive mass-produced article