In designing a specialized dictionary, the conceptual structuring of the field is extremely important. Concepts do not exist in isolation, they cannot be considered units of knowledge with independent existence, but they always enter into a relationship with each other, finding their identity in relation to a structured conceptual ensemble. The conceptual tree allows the identification of general concepts, of the first degree, then the relationship with the individual concepts, of the other levels, by establishing the hierarchy or other relations: cause – effect, purpose, part – everything, etc. The conceptual tree determines the contouring of the field, the rigorous delimitation of the distinctive features of some concepts and their univocal definition, being an effective tool in the design of specialized dictionaries.