I have a medical dictionary now.
Here's what I did:
There is a free database Openmedspel,(thanks Sunil, for putting me on the path, I had found it a long time ago but didn't figure out how to import it at that time) which has about 48000 entries.
I tried taking the userdic.thx file and opening and pasting with correct additions (tab I) but this could not be read by the spell checker.
Then I pasted into a blank chart and imported all 48000 (held down the enter button for about an hour) and have transferred the newly created userdic.thx file (now 648K) to AC and voila, I have a medical dictionary.
I have transferred it to several other computers and it has worked well.
Here is a link, hope it works well for everyone.
https://www.dropbox.com/sh/z1vxfny7khqr0kz/3bFTTRIA-INow as to the technical changing of properties .....