caste: [16] Caste has no etymological connection with cast. It is borrowed from Spanish and Portuguese casta ‘race, breed’, a nominal use of the adjective casta ‘pure’, from Latin castus (source of English chaste). The notion underlying the word thus appears to be ‘racial purity’. Use of casta by the Portuguese in India with reference to the Hindu social groupings led to its being adopted in this sense by English in the 17th century. => chaste, incest
