Perhaps you should try some spelling variations:
passiv » massiv, passiven
passive » massive, passivene
passiverer » massiverer, passivenerer, passiverwerb, passivieren, passagerer, passivener, passivelyer, passierter
passiver » massiver, passivener, passiven, passively, passiert
passieren » passiert, passiven
massiver » massive, massiven, massively

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: ((passiv OR passive) OR ((passiverer OR passieren) OR (passiver OR massiver))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((passiv or passive) or ((passiverer OR passieren) or (passiver or massiver)))".
• Adding a wildcard symbol may retrieve word variants: ((passiv or passive) or ((passiverer OR passieren) or (passiver or massiver)))*.