". . . In McManus’s view, the names of Edad and Idad clearly represent an ‘artificial pair,’ as we’ve already touched on, and he suggests these names came later — replacing the original letter-names. Seeing as the kennings for Edad and Idad both associate the letters with the yew (where Edad identifies the yew through éo, while Idad identifies it by another name, ibar), McManus has suggested the letter-names may have originally been something like *eburas (or *esox) and *iwas (which represent Primitive Irish reconstructions), where both of the names would then point to the yew-tree. Assuming this is the case, the letter-names of Edad and Idad that we’re familiar with today may then have been created as a way of trying to address the inevitable confusion between the two letters, in essentially having the same name — giving them a more separate identity while still acknowledging their pairing."
—A Guide to Ogam Divination by Marissa Hegarty
