The article deals with the particularities of the libertine vocabulary in A. D. Kantemir's “Russian and French Lexicon” which is not only the earlier specimen of the Russian-French Dictionary, but also one of the first secular-oriented lexicons in the 18th century Russia. The content of the Lexicon is considered in contrast to the French translated love fiction, which contributed most to the development of the “language of love” in the new secular Russian society. It allows to define the place that Kantemir's Lexicon takes in this process. The article analyzes a wide range of mechanisms that Kantemir uses in the aims of enriching the Russian language with the libertine vocabulary. In particular, the author of the article notes some cases of the secularization of slavicisms, which means rethinking the range of meanings of the words of Slavic origin. The article demonstrates such tendency as arbitrary use of prefixes and suffixes, which often offers examples of the author's word creation, or tendency to generating long rows of the synonyms including the words with different functional and stylistic characteristics. Special attention is paid to the fact of codification in the Lexicon of the vulgar, obscene vocabulary, which associates this work to the manuscript collections of the Russian erotic poetry, the so-called barcoviana, and attests the innovative character of the Lexicon in comparison with the Russian lexicographic tradition. A notable fact is the tendency to a limited use of gallicisms, which is not typical for Kantemir as writer and translator. Conclusions are drawn that Kantemir's Lexicon, though the obvious secular orientation and the orientation towards the French language as language of gallant communication, demonstrates the fundamental ability of the Russian language to produce its own and not use the borrowed vocabulary that serves the sphere of gallant relations.