defile vs darken

defile is a noun but darken is not a noun.

Word	Noun	Adjective	Verb	Adverb
defile	Yes	No	Yes	No
darken	No	No	Yes	No

As verbs, darken is a hyponym of defile; that is, darken is a word with a more specific, narrower meaning than defile:

defile: make dirty or spotty, as by exposure to air; also used metaphorically
darken: tarnish or stain

defile (noun)	darken (noun)
a narrow pass (especially one between mountains)

defile (verb)	darken (verb)
spot, stain, or pollute	become dark or darker
make dirty or spotty, as by exposure to air; also used metaphorically	make dark or darker
place under suspicion or cast doubt upon	tarnish or stain