Vocabulary Coinage in J.K Rowling's Works This study is taken up to explore the idea that coined vocabulary is one of the major reasons for the popularity of the Harry Potter series and that it enhances the linguistic creativity of its readers when the readers explore the meanings and etymology of coined words, which are mainly lexical items based on the root languages of English - mainly Latin, Greek and French. To explore this phenomenon, the text of all seven books was critically analyzed because the coined words are embedded in the story. This critical analysis was done keeping in view the Strict Relexification Hypothesis of Michel DeGraff, professor of Linguistics at Massachussets Institute of Technology. DeGraff has reevaluated the Relexification Hypothesis presented by Claire Lefebvre of Quebec University who has worked on Haitian Creole: developed as a third language through the interaction of two different languages (French and African Ewe) but with little interaction between the speakers of the two languages. Professor DeGraff’s reanalysis states that copying of lexical items of one socially superior language (superstratum-French) and its phonetic borrowing done as phonological representations by the socially inferior language (substratum-African Ewe) were not copied exactly, so with the passage of time, it became a third language, because the semantics of the borrowed lexical items changed as well. This was due to the exposure of the substratum speakers to the superstratum language (in this case, French). J. K. Rowling is a scholar of Latin, Greek and French languages, and is well-read in classical literature. This has led to the word coinages rooted in Latin, Greek and French having meanings based on these root words but to which the grammatical rules of English word-formation are applied. This has led to a separate Harry Potter language, words of which are used by the readers, as attested by book reviews, research papers and many websites. To determine the interest of the readers in coined vocabulary specifically, a survey was conducted for student readers and English teachers of private schools. The approximate age group selected was eight to 25 years. The results were analyzed through SPSS-14, and presented in the form of tables and pie charts.