Latin form: Nennius
1. Son of Don and Beli Mawr; legendary king of Britain, mentioned in the Mabinogion with Lludd, Llefelys, and Caswallawn, and in Geoffrey of Monmouth's History of the Kings of Britain under his Latin name Nennius. Legend says that he was turned into an ox for quareling with his brother Peibaw.
2. Welsh name of St. Nennius the historian.