Sarah, you might also want to bookmark http://gtb.inl.nl/ particularly if you will be dealing with many older Dutch records; when Google Translate doesn't return a result, or it returns something totally nonsensical I'll try putting the term in the search engine on the linked site, then I'll Google Translate those results to get a better idea of what a particular word might mean (or once meant, at least). As an example, the entry for "Fictief", run through Google Translate gives, in English:
↪1. Arbitrarily conceived, invented,
↪2. Which only benefit there be a consideration or computation value is assigned.
It's not perfect but definitely enough to get a sense of how the word might be being used.