Etymology

In law, the word real means relating to a thing (res/rei, thing, from O.Fr. reel, from L.L. realis "actual," from Latin. res, "matter, thing"), as distinguished from a person. Thus the law broadly distinguishes between "real" property (land and anything affixed to it) and "personal" property (everything else, e.g., clothing, furniture, money). The conceptual difference was between immovable property, which would transfer title along with the land, and movable property, which a person would retain title to. The oldest use of the term "Real Estate" that has been preserved in historical records was in 1666.
The use of "real" to refer to land also reflects the ancient preference for land, and the ownership thereof (and the owners thereof). This, in turn reflects the values of the medieval feudal system, which is the ultimate root of the common law.