Perhaps you should try some spelling variations:
passiver » passiven, passively, passiert
passiveren » passivenen, passivelyen, passierten, passivieren, passieren, passiverer
passivener » passiverer, passiven, passiverwerb
passioner » passione, passionen, massioner

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (((passiver OR passiveren) OR (passivener OR passioner)) OR passive).
• Adding a wildcard symbol may retrieve word variants: (((passiver or passiveren) or (passivener or passioner)) or passive)*.