There are several theories regarding the origin of the island’s name. There is broad consensus that “Kastello” derives from the Italian word “Castello,” meaning “castle.” However, different interpretations exist concerning the second part of the name.
One theory links it to the Italian word “rosso” (“red”), which may refer either to the island’s reddish rocks (despite their generally grayish appearance) or to the red emblem displayed on the coats of arms of the Knights of Rhodes at the castle gate.
Another possibility is the Greek word “rizon,” meaning “to take root,” potentially describing the mountainside on which the castle was built. It may also be associated with the French word “horizon.” It is suggested that the knights led by Folques de Villaret, who conquered the island in the 14th century, may have been inspired by the impressive panoramic views visible from the island and contributed to the adoption of this name.
