This article explores oronyms, proper nouns that designates parts of the relief, as a sub-category of toponyms within proper names. Beyond research works in the fields of historical linguistics and onomastics, few publications in linguistics have been specifically dedicated to toponyms. This sub-category of proper names itself is diverse and the present study focuses on oronyms. We first explain the specificities of oronyms due to their formal characteristics and their instable referent in a continuous geophysical space. We then explore how this type of proper names comes into being. This process, that we call toponymation, begins when a new relief proper name is proposed until it is commonly used in language and on maps. Along this long and complex process, we describe the numerous hesitations, mistakes and double naming occurrences before an oronym is stable and accepted. This will allow us to define the necessary conditions for the naming of relief.