From the Roman name Caecilius (see Cecilia). This was the name of a 3rd-century saint, a companion of Saint Cyprian. Though it was in use during the Middle Ages in England, it did not become common until the 19th century when it was given in honour of the noble Cecil family, who had been prominent since the 16th century. Their surname was derived from the Welsh given name Seisyll, which was derived from the Roman name Sextilius, a derivative of Sextus.