keen vs keenness

keen and keenness both are nouns.

Word	Noun	Adjective	Verb	Adverb
keen	Yes	Yes	Yes	No
keenness	Yes	No	No	No

keen (noun)	keenness (noun)
a funeral lament sung with loud wailing	thinness of edge or fineness of point
	a quick and penetrating intelligence
	a positive feeling of wanting to push ahead with something

keen (adjective)	keenness (adjective)
excellent
intense or sharp
having or demonstrating ability to recognize or draw fine distinctions
having a sharp cutting edge or point
painful as if caused by a sharp instrument

keen (verb)	keenness (verb)
express grief verbally