Nicely done. It's good to see that somebody is still keeping Latin Words for Mac up-to-date. The main problem for me is that the font is a little difficult to read; it would be nice if this were an option in the preferences.
In terms of ease of use, it would also be handy if you added a "Look Up in Interpres" service, just to save one more step. Also, rather than having separate keyboard shortcuts for switching to the Latin and English tabs, why not just use a common one such as command-D or command-L?
Also, a nicer icon would be appreciated (although I've changed it myself, so this obviously isn't a huge issue).

Being a heavy library user, this is probably one of the single most helpful programs I've run across in a long while, fixing something I didn't even know could be.
Although I couldn't initially get my library to work, the developer e-mailed me back in the same day and fixed my problem. This the kind of thing that truly defines the Mac!