Or who caused that he should not go to the dales of Defwy,
They know not the brindled ox with the broad headband,
Whose yoke is seven-score handbreadths.
When we went with Arthur of mournful memory,
Except seven, none returned from Caer Fandwy.

No one has satisfactorily discovered the meaning of this verse.

Cyfarwydd

[W] A professional storyteller like the seanchaidhe (or seanchaí) of Ireland.

Cyfwlch

[W] One of three warriors who possess the brightest and sharpest weapons at Arthur’s fortress. The others are Bwlch and Syfwlch.

Cymidei Cymeinfoll

[W] “The big-bellied battler.” The wife of Llasar Llaesgyfnewid. She and her husband appear to be deities of war for they own a magic cauldron. If a slain warrior were cast into it he would come forth alive again except that he would have no power of speech. When they were in Ireland, Cymidei would give birth to a fully armed warrior every six weeks. Matholwch of Ireland tried to destroy them but they escaped to Britain where Bran gave them refuge. In return they gave him the cauldron. When Efnisien insulted Matholwch on the eve of his wedding to Branwen, Bran gave him the cauldron as a means of atonement.

Cymon

[W] A warrior at Arthur’s court. He appears in a Welsh version of “Le Chevalier au lion” of Chrétien de Troyes. He comes across a black man with one foot and one eye, bearing a mighty club, in a glade in a forest with wild animals, stags, and serpents feeding by him. Cymon was looking for a combat and the man told him to go to a fountain, take a silver bowl he would find there, and fill it with water. The water must then be thrown on a nearby marble slab. A thunderstorm would follow, and the singing of enchanted birds, and a Black Knight would appear. Though couched in medieval guise, many things about the tale are of earlier Celtic origin. The Black Knight defeats Cymon, who returns to Arthur’s court where Owain ap Urien is fired by his tale and sets out to defeat the Black Knight. The rest of the story belongs to Owain, except for when, after he had been missing from the court for three years, Arthur and Gwalchmai and a band of warriors, with Cymon as their guide, set forth to find him. They eventually find him well and prospering in the Castle of the Fountain.