uninvited disturbing guests

My question to admins
Is it possible to block individual words/phrases?
The guests always use the same words,
this could possibly prevent them from posting at all
just an idea

Turquoise

Yes, we have banned word list in our site... Just you can not write these words in here but they will use like f*** or sh***

Banned words mostly not working... Also it is not banned the new users just they can not use these words thats all

Also again guests can not write on our site (No reply or no make comments  to posts)