Surnames among the French nobility are often composed of patronymic names, titles, and noms de terres (names of lands), joined by the preposition ''de.'' The aim of this article is, first, to analyze the articulation and devolution processes of these different components, as well as the meaning they could have had in the ancien regime. Second, the article examines what happened after the French Revolution to such names. The example of a court proceeding in the nineteenth century, involving two families and dealing with the usurpation of a nom de terre, leads to questions concerning the relations between law, common use, and the many functions of proper names in contemporary society.