cognizance vs ken

cognizance and ken both are nouns.

Word	Noun	Adjective	Verb	Adverb
cognizance	Yes	No	No	No
ken	Yes	No	No	No

As nouns, cognizance and ken are synonyms defined as:

cognizance (noun)	ken (noun)
having knowledge of	range of what one can know or understand
range of what one can know or understand	the range of vision
range or scope of what is perceived