Formal:
* Hush - This is the most common and straightforward way to indicate silence.
* Quiet - This word is used for general silence or to ask someone to be quiet.
* Silence - This emphasizes the absence of sound.
Informal:
* Shhh - This is a common way to indicate silence in a playful or casual way.
* Ssssh - This is similar to "Shhh" but a bit more drawn-out.
* Shh! - This is a more emphatic way to demand silence.
* Psst! - This is a softer, more subtle way to get someone's attention.
Onomatopoeia:
* Sssss - This is a sound effect that mimics the sound of silence.
Other:
* Quietly - This can be used as an adverb to indicate that something is done silently.
The best way to spell the sound "shssss" depends on the situation and the intended meaning.