MODRON (standardized modern form)
Of the women discussed here, only Modron is clearly a mythological addition to an otherwise historic context. Peniarth Ms. 147 (1556) includes a legend that Urien Rheged had twins by "the daughter of the king of Annwn" (the Welsh underworld), and this mother is specifically identified in the triads as Modron verch Afallach (Bromwich TYP no. 70 ). Elsewhere in medieval Welsh literature, Modron appears as the mother of Mabon, a pair generally considered to preserve a divine mother and child (the names Modron and Mabon derive from roots meaning "mother" and "son" with the suffix -on typically found in divine or semi-divine names). Afallach generally appears as a son of the legendary Beli Mawr, and the namesake of Ynys Afallach, an alternate name for the island of Avallon. The story of Urien's encounter with Modron further enhances the other-worldly aspects: Modron has a destiny laid on her that she must wash at a ford until she has a son by a Christian. (The otherworldly woman washing at the ford is a repeating motif in both Welsh and Irish legend.)
The children of this encounter were Owein and Morfudd, and while we must exempt Modron from our list of plausible women's names for this period, the children have names that are otherwise unexceptionable in this context, and there is no reason to assume that they are spurious.
Textual Sources
In relation to this specific figure, the name appears as:
[M]odron merch Auallach - Peniarth Ms. 47Modron ferch Avallach - Peniarth Ms. 50
The mythological figure of Modron can be found in many other contexts, presumably going even as far back as Gallo-Latin references to the matrones in dedicatory inscriptions.
Linguistic Analysis
Because this name is not being recommended as a plausible human name, no reconstructed written and spoken forms are offered.