Nautical activities, which started with the capture of port cities in the Anatolian geography in the 13th century, increased their importance day by day in the social, economic and cultural lives of the Turks. Especially as of the 14th century, the increase in the dominance of the Ottoman Empire in the seas and the progress of commercial relations with Italian/Genoese merchants in the south caused many terms to be quoted from the Venetian language and Italian. A common language, a lingua franca, was formed with the contributions of the languages of the countries with which the sailors engaged in nautical activities in the Mediterranean interacted, including Turkish. After the second half of the 15th century, the Turkish sailor language developed rapidly. The use of words borrowed from languages such as Arabic, Persian, Greek and Italian in the Turkish sailor language has become widespread over time and these terms have been transferred to ordinary language. Some of the maritime terms, which have become widespread in Turkish, have moved away from their real meanings and have been included in the vocabulary of slang by being nominative or idiom. In this study, the lexemes that are the nautical term and which are included in the vocabulary of slang are discussed. Lexemes covered in the study were examined in terms of structure and semantics; it has been classified thematically and conceptually and evaluated in terms of sociolinguistics. Slang aims to use the words selected from the standard language’s vocabulary by deconstructing and using these words by encryption. In this respect, the Turkish nautical language, the majority of which is borrowed from the languages of the civilizations that were pioneers in nautical, provided an important material for slang. Although maritime terms belong to the nautical field in external structure, they have a slang meaning in the conceptual and intellectual context. Thus, what is implied by these terms used in the colloquial language is no longer the term meaning of the word, but its slang meaning. These words, which include already the feature of enciphering due to their term meaning, have been transformed sometimes to slang even without semantic change.