From a specialized communication perspective, contemporary theories of Terminology conceive variation as an inherent feature of the term. For such reason, it is plausible of analysis, taking into consideration cognitive and contextual factors such as chronological evolution, level of specialization, viewpoints, among others. Nevertheless, variation in dictionaries remains underrepresented, due to the prescriptive tradition that dominated terminology research. In this sense, the present paper aims at analyzing the phenomenon of term variation in the domain of Lexicography in Brazil and at offering a proposal for its lexicographic representation in a specialized lexicography dictionary for learners. Thus, we have carried out analysis of explicit term variation of a corpus of texts of Brazilian Lexicography with a view to observing the cognitive consequences emerging from the use of such variation, as well as the possible cognitive factors that may originate this variation. Finally, we propose the representation of term variation in the microstructural organization of the Brazilian Lexicography Dictionary.