shush vs silence

shush is not a noun while silence is a noun.

Word	Noun	Adjective	Verb	Adverb
shush	No	No	Yes	No
silence	Yes	No	Yes	No

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

Other hypernyms of shush include hush, hush up, quieten, shut up, still.

shush (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)

shush (verb)	silence (verb)
silence (someone) by uttering `shush!'	cause to be quiet or not talk
	keep from expression, for example by threats or pressure