The article presents an analysis of the prefaces of seven interpretation dictionaries of the Tajik language appertaining to 11th–15th centuries in relation to the criticism of proceeding dictionaries and explication of linguistic ideas contained in the formers. It is marked that the inceptions of the criticism referring to the proceeding dictionaries can be found already in the first interpretation dictionary of the Tajik language “Lughati Furs”. In the introductions to the interpretation dictionaries of the 13th century “Madj­muat al-Furs” and especially to “Sihoh al-Furs” there are presented well-grounded and substantially argued considerations concerned with a necessity of adducing illustrative poetical material for a right reading of an interpreted word. Very interesting judgments in regard to the nature of Arabic and Tajik languages are adduced in the introduction to the dictionary “Meyori Djamali”. There is underscored a similarity of critical remarks between the authors of the dictionaries “Madjmuat al-Furs” and “Sihoh al-Furs” though you can affirm with an adequate share of assuredness that Hindushokh Nakhchuvani, the author of the dictionary “Sihoh al-Furs” was not acquainted with the lexicographical work “ Madjmuat al-Furs” by Khadjib Hayrot, just as the latter had no idea about the dictionary created by Nakhchuvani. It is marked especially that the authors of “Farhangi Kavvos”, “Dastur al-afozil” and “Donishnomai Kadarkhon” don’t mention the predecessors and, respectively, any criticism of the lexicographical productions created beforehand is absent in their works.