Abstract: Ethnicity is a complex phenomenon. It is a highly controversial, disputable, problematic term that does not have any fixed meaning and is used as a less emotive term for a race. Ethnicity is a social construct like race, but the main difference is that race refers to phenotypical differences, whereas ethnicity refers to cultural differences. Ethnicity helps an individual to identify with a larger group, and one’s ethnicity may identify an individual. Too many writers like Max Weber, Michael Brown, Wsevolod Isajiw, etc. have discussed many features to define 'ethnicity.' To explain and outline an apparent meaning for ethnicity, authors like Fredrik Barth, Abner Cohen, Michael Hechter, etc. have postulated different approaches such as primordialism, instrumentalism, materialism and constructivism. Robert E. Park has contributed to the theory of ethnicity by focusing on assimilation theory. Authors like Omi and Vinant have openly opposed this theory and considered the immigrant as the basis of ethnicity. The chief motive of this paper is to discuss the shifting meanings of ethnicity and to depict the purpose behind the divisions based on ethnicity.