come down vs canker

come down is not a noun while canker is a noun.

Word	Noun	Adjective	Verb	Adverb
come down	No	No	Yes	No
canker	Yes	No	Yes	No

As verbs, canker is a hyponym of come down; that is, canker is a word with a more specific, narrower meaning than come down:

Other hyponyms of come down include wan, contract, get, take.

come down (noun)	canker (noun)
	a pernicious and malign influence that is hard to get rid of
	an ulceration (especially of the lips or lining of the mouth)
	a fungal disease of woody plants that causes localized damage to the bark

come down (verb)	canker (verb)
get sick	infect with a canker
be the essential element	become infected with a canker
criticize or reprimand harshly
move downward and lower, but not necessarily all the way
fall from clouds