Thanks, David. I reread the DIL entry with 'boithus', and I see how I got confused.
The next part --
Nach mod donbered dia bélaib, dolinged míl mbec íarsin lind dochum a bél. Ó ra uccad ó bélaib, nacc ní
i nneuch, sceinti lea hanáil o chud.
Van Hamel's notes --
"Donbered stands for dondbered, where ,'d' is a neuter infixed pronoun and -n- denotes the nasalization required
In a dependent sentence expressing manner or quality."
Referring to'bél' -- " In Old Irish the singular denotes "a lip", the plural "the lips or the mouth".
The other MSS have 'naccnimneuch' and 'nacni in deoch' which show that the "expression was
not clear to the scribes.
My note -- LU has 'ho chud'.
This story reminds me of another Irish story about the birth of a girl. A farmwife drinks a cup of buttermilk with a fly in it, gives birth to a girl; she grows up and meets a man in the mist who takes her back to the Otherworld.
All comments welcome. Liz