"Nomina im Indogermanischen Lexikon" quote Lat. paternus (but they mention that this has been suggested to be a younger formation) and Germanic *fadarnio- in Old Norse faðerni "paternal..." and OE fæðerncynn "parents, ancestors".
From: Old-Irish-L <[log in to unmask]> On Behalf Of Christopher Gwinn
Sent: 06 January 2019 21:17
To: [log in to unmask]
Subject: Re: The Athirne and Midir incident
> But Celtic *φateroni̯o- would yield **Aithrinne in Old Irish. Aithirne
could continue *φaternii̯o- < *ph₂terno-,
Is *ph₂terno- attested in any other IE language? de Vaan, Etymological Dictionary of Latin and the other Italic Languages, Brill, 2008, p. 450, suggests that paternus was a Latin development ("paternus was probably formed after māternus."). IIRC, in Latin paternus and maternus, there was early syncope of a vowel between -r- and -n-.
- Chris Gwinn