Kermiss

For as long as I have been alive we have spelled it Kermiss. But the tradition here in Wisconsin dates back to the first being held in Rosiere in September of 1858. As you can see by the late 1930's Wisconsin Belgian's had a couple spelling varieties (I've also seen; Kermiss, Kermis, Kermess, Kirmess) :

The proper French/Walloon spelling is Kermesse, and it sounds much like how we say it in English (Pronunciation by Pat91). The Flemish spell it Kermis.

And in case you need to review the history: