Chaturvarna

A theoretical construct of Brahmin scholars to describe and categorize (varna) the complex social arrangement of which they were themselves a part.

In the absence of a better word, varna was then translated as caste by the Europeans, with its connotations of racial purity. Contrary to popular belief, historically there was a great deal of mobility and intermingling within Indian castes, other than Brahmins, largely based on economic or political status of the concerned group.

Excerpted from the Wikipedia