This article analyses the fundamental concepts of general derivatology from a conceptual and terminological perspective. Since derivatology operates with its own intermediate entities for both the lexical and grammatical systems, the author attempts to highlight the necessity and importance of using a univocal metalanguage to designate the categories, processes, and phenomena specific to derivatology. In this regard, the controversial concepts of derivatology concerning the status of level/interlevel, the identification of its basic unit, and the terminological determination of the concept under study are treated in depth.