Abbreviation in the pattern is unclear

Hi, I have a problem:
my English pattern uses the abbreviation "bun," but when I Google it, the German translation that always comes up is "Brötchen".
It would be great if someone could explain this term to me.
I’ve run into this problem quite a few times in patterns.

Hmm. I’ve looked it up in every list of abbreviations I know and haven’t found it. Is there a list of abbreviations and their meanings anywhere in the pattern? The author herself is probably the best person to help you with this.
Just a shot in the dark: It could be that “un” stands for “under needle,” meaning something like “B under needle” (similar to “yarn over needle”). Is this a knitting or a crochet pattern? Is it perhaps a brioche pattern, where for some variations you slip stitches and have to bring the working yarn under the needle in front of the work beforehand? As I said, that’s just a shot in the dark.

I’d also write to the author.

What exactly is it supposed to be?

I think it was originally a Russian pattern, since the other stitches are labeled “sbn” and “ssn.”

A little mouse/rat for a keychain