Studying the etymology of special words in Persian language is of great significance from different aspects. In the present article two words of Sagsar and Bozgosh have been studied by the writer. Sagsar has been applied in epic verses both as the name of a place referring to creatures having a dog head and human body and as a proper noun referring to Demon. Beside heroic poets, other poets have also used the word "Sagsar"in their verses. This research will try to find an answer to the following questions: "Who introduced these two words in Persian literature?" and "What is the difference of applying the word Sagsar in epic and non-epic verses?" Based on our findings in this research, the word Sagsarwas used in Ferdowsi'sShahnameh for the first time. The only literary source, in which the word "Bozgosh" has been used is also Ferdowsi'sShahnameh. The existence of places called Sagsar and Bozgosh in geography is also discussed here in this study. The difference in the function of Sagsar concept in epic and non-epic verses as well as its semantic and content transition will also be studied in the research.
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