Scientific Dictionary or term list for word processors?
 

I've been in college for a number of years now, and written quite a few technical papers and reports. Every time I do, however, I have to teach MS Word a whole new vocabulary due to the non-common terms we use.

I've seen dictionaries for sale online that contain loads of science-based words and can be imported into word processors, but they cost upwards of $50. Does anyone know of a site with a free downloadable scientific dictionary, or even a list of terms that I can import into the custom dictionary in word?

In case anyone's wondering, I deal with engineering and biological terms, as well as fuels.