The term “Kurd” which is conceived as one of the ethnic groups in the Middle East nowadays, has an ambiguous meaning and application in the sources of the Islamic period. In the contemporary era, some researchers have employed the present meaning of the term “Kurd” (i.e. an ethnic group) in historical studies. Some researchers, on the other hand, have discussed the various interpretations of the term in different sources. They, however, have not elaborated on their views and have paid little heed to the evolution of the term in different sources. This study examines the various applications of the term in Islamic sources based on the semantic signs using a historical-analytic method. The results show that the term “Kurd” has been used to refer to both an ethnic group and a group of people with nomadic life style in the first centuries of the Islamic period. However, the term stopped to be used in the sense of nomadic people gradually and since the seventh century AH onward, it has been used with the meaning of an ethnic group.