Sociological works on ethnicity have paid much attention to concepts such as “ethnic group” and “ethnicity”. But, they have not thematized the meaning of the term “ethnic” in its own right. This paper renders the term “ethnic” problematic, and focuses on the complexity surrounding its usage both in everyday life and in academic research. It starts with an analysis of the meaning of the word “esunikku” (an alphabitical representation of the English word “ethnic” in Japanese) in everyday life. Noting that the everyday “esunikku” has meanings quite different from those of the academic, it examines closely general usages of the term in relevant sociological literature. In particular, it focuses on (1) the “neutrality” of the academic term in relation to its popular connotations and nuances (which often involve imageries of racial or cultural discrimination, on the one hand, and colorful images of bodily pleasures associated with ethnic food, fashion and music, on the other) and (2) the relationship between “race” and “ethnicity”. In addition, the meaning of the word “ethnic” in its popular use in the United States is examined. These analyses show that the academic concept of “ethnicity” is closely associated with the idea of “cultural pluralism”, but that both of these “clean words” have problems of their own. The paper concludes with some suggestions for sociologists to rethink about the problems of discrimination, cultural pluralism and the use of language in sociology.