In Welsh mythology, who/what was Euroswydd? Perhaps a god or some other sort of supernatural entity? Is there any information by this dude apart from the story about him somehow imprisoning the sea-god Llŷr so that he could have his way with Llŷr's wife [and half-sister?] Penarddun, thereby fathering the sons Nisien and Efnisien upon her? No payback from Llŷr at any point? Also, any idea what his name means?