This dictionary -one of the most complete in the world in its speciality- is characterized by the richness and diversity of the information it gathers, as well as the variety of different level audiences it addresses. From the most elementary notions to mathematical formulations and concepts in the course of training, the subjects that are part of our secondary, university and technical education programs are carefully and extensively collected, punctually insisting on the relationships that link pure mathematics with the experimental sciences and their industrial applications. It is thus possible to cover a wide spectrum of subjects, which encompass the fields of logic, sets, arithmetic, combinatorics, algebra, geometry, analysis, mechanics, probabilities, statistics... Such heterogeneity is expressed in a rich vocabulary of 7,600 key terms -each referring to a different notion, main or secondary, centered on a definition-, as well as in the symbols and formulas that correspond to them. Through definitions, examples, results, comments and illustrations -approximately 700- the user of this book will be able to essentially achieve a complete and comprehensive vision of each notion, as well as how many concepts are related to it.