Originally Posted by Philantrop
Just like you described: Highlight the word. Among other options, I get a "Define" option which does a Google lookup.
BlueFire Reader 1.9 here.
I see now that it always worked, just not for a book I sideloaded from the library. I upgraded to 1.9 after borrowing the book and have yet to sideload another library book after the upgrade, but I doubt that's the problem.