Perhaps you should try some spelling variations:
passiver » passive, passiven, passively
passiveren » passiveen, passivenen, passivelyen, passieren, passiverer, passiven
massiv » massive
passivieren » passivierende, passivierung, passieren
massigen » massiger, massige, massigung
massigeren » massiger, massivere, massierer

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 massiv) OR ((passiveren OR passivieren) OR (massigen OR massigeren))).
• Adding a wildcard symbol may retrieve word variants: ((passiver or massiv) or ((passiveren or passivieren) or (massigen or massigeren)))*.