strange word in Dutch language

Beautiful is in the Dutch language "mooi". In German beautiful is
schoen and in Flemish "schoon".

The word "mooi"is a typical word from the north of the Netherlands.
It is used in German coast countries like Oldenburg, Sleeswijk-
Holstein till the Danish border. It does not exist in the Scandina-
vian language. It is not related to any language with exception
of the Baltic-Slavic word "muitd" means washed. Who can give
more information about the origin of the Dutch word "mooi"?