Here are some things to keep in mind:
* Context is crucial: The meaning can shift depending on the context. It could refer to people who are celibate, those who live a life of purity, or even those who adhere to a specific religious doctrine.
* Cultural understanding: The concept of "chastity" can be interpreted differently across cultures and time periods.
* Modern usage: The term "los castos" might not be commonly used in everyday conversation.
To fully understand the meaning, you would need to see the phrase in context.