Your best bet would probably be a variety of medieval Latin and writer specific dictionaries.
J.F. Niermeyer, Mediae latinitatis lexicon minus
http://www.amazon.com/Mediae-Latinitati ... 9004112790
There are editions of this going back to the 1970s. The definitions are in English, German, and French.
An outdated (though now uncopyrighted) work is the 1678 Glossarium mediae et infimae latinitatis
done by Charles du Fresne: http://en.wikipedia.org/wiki/Charles_du ... r_du_Cange
Here is a digital edition of du Fresne that may be of use to you:
Roy Deferarri, Latin-English Dictionary of St. Thomas Aquinas
http://www.amazon.com/Latin-English-Dic ... 974&sr=8-2
This will assuredly have most of the scholastic terms you're looking for.
Here is an online Thomas Lexicon, but it's in German:
Here is an online Neo-Latin wordlist, "from Petrarch to 1700" that may have some words you need.
http://www.lrz-muenchen.de/~ramminger/v ... o_engl.htm
I hope you have access to an academic library, because I can't imagine these will be easy to find otherwise.