'caste' originates from Portuguese and Spanish, specifically the word 'casta', where 'casta' meant 'breed, lineage, race'.

'caste' entered English in the 16th–17th century from Portuguese/Spanish 'casta', which itself was used in colonial descriptions of social groups in South Asia; over time the English word 'caste' came to refer broadly to hereditary social classes and their system.

Initially, it referred to 'lineage' or 'breed' ('casta'); over time it evolved into the modern sense of a fixed hereditary social class or the system of such classes.