A U.S. Copyright Office brochure (http://www.copyright.gov/circs/circ34.pdf) says, "Copyright law does not protect names, titles, or short phrases or expressions," which would seem to leave authors home free to run with magocracy. But maybe not.
Anyone know how to determine whether a word is fair game?
Search terms used: "magocracy and copyright," "copyright single word," "magocracy origin." (I also threw "magocracy" into Google Books and got 270 hits, but I can't decide whether that answers the question sufficiently.)