http://www.ehu.es/ojs/index.php/ASJU/article/view/1694/1328In the decade of the sixties, the main concern of the experts in Basque language was how to unite the speech community. However, after forty years of Standard Basque, the objective is to develop a language that is well adapted to each register. The lexis is the key in the functional development that the adaptation to each register requires, and that is exactly what we shall study in this work. We shall analyse, from the point of view of functional diversity, the methodology of the Standard Basque Dictionary, the purpose of which is to organize the standard Basque lexicon. We reach the conclusion that Standard Basque has taken certain steps to get closer to the functional variability...