Rated 4 out of 5 stars
This is a really handy add-on. The old way of looking stuff up was pretty easy, but this is way easier. Very useful for learning more words.
I would give it five stars if the pop-up window was movable. (I keep my task bar on the left side of the screen and the first bit of the quickwiki pop-up appears under it.) It would be nice if quickwiki was zoomable too.
But over all a very hand add-on.