shout down vs silence

shout down is not a noun while silence is a noun.

Word	Noun	Adjective	Verb	Adverb
shout down	No	No	Yes	No
silence	Yes	No	Yes	No

As verbs, silence is a hypernym of shout down; that is, silence is a word with a broader meaning than shout down:

Other hypernyms of shout down include hush, hush up, quieten, shut up, still.

shout down (noun)	silence (noun)
	the absence of sound
	a refusal to speak when expected
	the trait of keeping things secret
	the state of being silent (as when no one is speaking)

shout down (verb)	silence (verb)
silence or overwhelm by shouting	cause to be quiet or not talk
	keep from expression, for example by threats or pressure