Yiddish. Pronounced kuh-LUSH-iss.
Can be used as a noun or an adjective to describe something that is very disgusting, ugly, gross.
Proper use:
When my uncle, as a child, bought a chameleon, my grandmother immediately deemed the creature to be kulushis. Since he never chose a name for the chameleon, it was just called Kulushis. It was a kulushis creature (adjective) and it was a kulushis (noun).