The first letter "c" should not be capitalized, but there's unfortunately a limitation from Wikipedia's side.
It stems from the polish word for "silent (masculine)", which is originally written as "cichy".
"Ch" and "h" are pronounced the same in polish and are a common source of spelling mistakes.
Although in my case that was simply an artistic choice.
My first nickname ever was "daw00", yet when I was creating a Minecraft account I've seen it as childish, so I wanted to give myself more "mature" name. I found the word "silently" and thought it sounded cool. Back then I didn't took into account, that it's an adverb that is going to be used as a noun.
I don't know what posessed me as a child but I wan't born in 2000, I'm actually from 1998.
I added a suffix "PL", because for some reason that's what a lot of polish people did. This becase an issue, where my nickname "silenltyPL" would attract a lot of unwanted attention in League of Legends years later. I decided to change it to "cihy", since that's what my friends were verbally calling me anyways.
You would think Poles would recognise my nationality, but I've been asked maybe once or twice after my nickname change.
Technically, it's pronounced /ˈt͡ɕi.xɨ/, but I understand not everyone is able to comfortably create those sounds, so just do your best and have fun.
If you want a guideline, I'd say "chi" as in "tai-chi" followed by "hy" as in "hymn".
