The 6-letter synonym for oliedom is:
STOM
It is a Dutch word that means “extremely stupid” or “primordial stupid”. It is a more emphatic and insulting word than “stom”, and is often used in a humorous way.
Here is an example of how to use “oerdom” in a sentence:
Die man is zo oerdom dat hij denkt dat de aarde plat is.
(That man is so oerdom that he thinks the earth is flat.)