Don’t confuse it with Mix or anything like that, even though they do sound the same. But this is how Mx is pronounced. What is Mx ? This a gender neutral title or in other words, an honorific that does not indicate any gender. So along with Mr, Mrs, Ms, Miss etc., we also have Mx now. This was news to me. But looks like Royal Bank of Scotland has already started to use this in their forms.
There a couple more according to this Wikipedia article on Gender Neutral Title. English sure has evolved a lot now, hasn’t. Instead of figuring out new titles, why don’t we just get rid of them?