Same in English.
I’m not sure, though, that the English “shhh” is onomatopoeia. What sound does “shhh” emulate?
Thus far I’ve counted three variations in this thread:
- Typical hushing, like in a movie theater
- More commanding hushing, like parent to a child
- A small hushing sound like a nudge to let somebody know they should be silent (I actually recognize the difference, it is different, but I have difficulty in phrasing it in a way that makes it different from the normal hushing)
In Russian: Тссссс (pron. “tsssss”).
What’s an onomatopoeia is writing it like that. In Spanish we say that someone is chistando whether the actual noise they made was shhh, chis, chs or chischis - these last four are onomatopoeias, since they try to reproduce the actual phonemes being used, but the verb chistar itself is not, as it doesn’t.
I would understand it the other way around. The word chistar is onomatopoeia since it’s a word that represents a given sound. Shhh, chis, chs or chischis, and so on are the actual sounds themselves. Similarly, the sound a cow makes is whatever it is, just a sound, but the wood moo is onomatopoeia because it’s a representation of that sound. I’m not saying I’m right. It could very well be that the situation is the opposite of what I thought it is.
You seem to have the definition right but the concept wrong, and I have no idea how is that even possible. An onomatopoeia is a word which attempts to reproduce a sound exactly - which chistar doesn’t, but moo or chis do.
According to the Wikipedia, “An onomatopoeia […] is a word that imitates or suggests the source of the sound that it describes.”
The way I understand this is that onomatopoeia is a sort of interpretation of a sound that makes the original sound pronounceable or grammatical or whatever. It seems to me that chistar does this, and so, it is an onomatopoeia. Shhh and the like are the sounds themselves. Shhh doesn’t suggest the source of the sound shhh. Shhh is the sound of origin. There’s nothing about the sound shhh that suggests silence. Or maybe it does? Is that what I’m missing?
I think Hebrew is the same - shh = sheket. It’s probably the most-often Hebrew word used when I visit my first grade son during his lunchtime. 
“Shh” doesn’t suggest silence, but it imitates the sound someone uses to call others to silence.
Meow/miau is an onomatopoeia. Maullar is not. Woof/guau is an onomatopoeia. Ladrar is very much not.
In Finnish, shhh, shhht or hys.
“Shh” doesn’t imitate the sound someone uses to call others to silence, it IS the sound someone uses to call others to silence.
I’m taking your word for this, since you live there and all, but in all my 30+ years of exposure to Japanese language, people and TV programs, I have never heard of that.
I’m going to ask my SO tonight. The only thing I’m familiar with is ‘urusai’, which I have taken to mean ‘shut up (because I don’t like what you’re saying)’ most often, but sometimes I have heard it used as ‘(something or other) is noisy’.
Roddy
In Hebrew it’s pronounced “seh-ket.”
I think this is my first post in about 5 years…
Right. And you write it phonetically, which is what an onomatopoeia is. Someone writing phonics is using onomatopoeias.
North German: pst
South German: pscht
Greek: ssst or sout (soot, with a very short oo)
Tagalog has “pwisit” which I don’t think is a word, but it’s not quite as simple as “shhh”