/ kɑːst; NAmE kæst/ noun
1.
[ C ] any of the four main divisions of Hindu society, originally those made according to functions in society :
the caste system
high-caste Brahmins
2.
[ C ] a social class, especially one whose members do not allow others to join it :
the ruling caste
3.
[ U ] the system of dividing society into classes based on differences in family origin, rank or wealth
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WORD ORIGIN
mid 16th cent. (in the general sense race, breed ): from Spanish and Portuguese casta lineage, race, breed, feminine of casto pure, unmixed, from Latin castus chaste.