Meaning A boy's name of Welsh origin, it means "Legendary son of Beli." Origin of Casswallawn Welsh +-100%Zoom level changed to 1 Popular Middle Names Pronunciation 🔊 Listen Casswallawn Similar Names Caswallon Rhun Llevelys Nynnyaw Powell Camedyr Cawrdav Cnychwr Cubert Culhwch Year by Year Popularity of Casswallawn