castel

Castel is a term with multiple uses in toponymy and onomastics. Etymologically, it derives from the Latin castellum, meaning a fortress or small castle. In several Romance languages, the root appears as Castel (Italian and Occitan-influenced toponyms), Castello, Castelo, or castell- in compound names. In place naming, Castel often signals a site with a historical fortress or fortified residence. In Italy, numerous towns and localities begin with Castel, and notable examples include Castel Gandolfo in Lazio, Castel San Pietro Terme in Emilia-Romagna, and the fortress town of Castel Sant'Angelo in Rome. Similar toponyms appear in Switzerland and southern France, reflecting medieval fortifications.

Castel is also a surname in various countries, typically indicating ancestral ties to a place named Castel or to a fortress. As a proper noun, Castel appears in many geographical names and can be capitalized when part of a specific place name.