Perhaps you should try some spelling variations:
passiverer » passiverwerb, passieren, passagerer, passivener, passivelyer, passierter
passivieren » passivierende, passivierung, passieren
passivene » passiven, passiveand, passively
passiver » passiven, passively, passiert

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: ((passive OR (passiverer OR passivieren)) OR (passivene OR passiver)).
• Adding a wildcard symbol may retrieve word variants: ((passive or (passiverer or passivieren)) or (passivene or passiver))*.