silence vs shout down

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

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

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

Other hyponyms of silence include shush, calm down, lull, gag, muzzle.

silence (noun)	shout down (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)

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