Yiddish question

I want to use a Yiddish word I've never heard in real conversation; I found it in an online dictionary. If no one actually uses the word, I might feel silly having my character say it. The word is "mossik," meaning, among other things, naughty little boy.

My more general question is about the appropriateness of pulling words out of a dictionary like that. I don't mean the mechanics of constructing a sentence with it - I mean being unnatural.

Thanks! It was spelled "mossik" when I first saw it. I searched online for "mazik" and found a very useful article. Yiddish is more likely spoken then written, so I'm not surprised to see the spelling variations.

It's a great name for a cat.