Likely related to Castina or Castine, from Latin castus meaning pure or chaste.
Castina is likely related to castus, the Latin root meaning pure or chaste, and it may also echo names such as Castine. Like Casta, it belongs to the long family of virtue-based names that turn moral ideals into personal identity.
The form feels a little more ornate and name-like than the root word itself, which helps it move from vocabulary into naming. Castina has a stately, slightly formal sound. It feels rare and almost literary, as though it could belong to a historical novel or a family line that favors classical names with a soft feminine ending.
That balance between Latin severity and melodic finish gives it charm. It suggests refinement, composure, and a kind of old-world polish without sounding overly familiar.