This study comes into six chapters. The first chapter tells us the drawbacks of lexicography and its methods. It includes the objectives of choosing this topics and some information about the history of Arab lexicographers and the development of lexicography throughout history till the decline of Arabic language as a result of the decline in all aspects of life in the Arab world which were caused mainly by political reasons. The second chapter discusses the problem of compiling lexicon since Ahmed Faris Shidyag. In this chapter we have tried to discuss the problem with regard to the content and the lexical order. Moreover, we have considered the growing importance of this issue after the renaissance. The third chapter tells us about the most important lexicons which are prepared by Cairo Associate to solve problem of Arabic lexicon. The chapters also includes information about the Cairo Associate, its objectives, the types of dictionaries and their importance. The fourth chapter deals with the content of Al-Ma'jam Al-Waseit with regard to its size, the vocabulary, the historical developments taking into account, the technical and technological terms. This entices us to discuss the different varieties of Arabic, namely, standard Arabic and colloquial Arabic, borrowing, transliteration, Arabicised words, and the coinages. One of the most important issues which have been incorporated in this chapter are the sources and references consulted when compiling the lexicon. The thesis talks in its fifth chapter about an issue which has not been discussed before in the field of lexicography, namely the phraseology of the lexicon regarding the types of texts and their individual items. The sixth chapter deals with a topic, which is equally important. Thus the question of Arabcisation which has overwhelmed the researchers and learners recently, because of the new inventions and urgency to name them. The conclusion highlights the results of the thesis.