What is a "prix fixe menu?"

I've read this now in several descriptions of the PR, as well as in the book Lessons in Service from Charlie Trotter, written by Edmund Lawler. I fiqured it would be good to know what it means:

prix fixe (prē' fēks')
n., pl. prix fixes

1. A complete meal of several courses, sometimes with choices permitted, offered by a restaurant at a fixed price.
2. A fixed price charged for such a meal.

Actually, it makes sense.