Cast means to throw, and names the performers in a play or film, and the plaster support for a broken bone. Caste with an E is a hereditary social class, associated particularly with South Asian society. Only the social sense takes the E.
The core difference
A very broad English word, and a narrow borrowed one.
- cast — throw: cast a line; the performers: an all-star cast; a plaster support; to shape molten metal.
- caste — a hereditary social class: the caste system.
Where caste came from
Portuguese casta, meaning race or lineage, applied by Portuguese observers to the social structures they encountered in India. It is a European term for an Indian system rather than an indigenous word, which is part of why it is contested as a description.
The idioms
Cast doubt, cast a vote, cast aside, cast iron — all the throwing or shaping sense, all without the E.