Etymologiadata:imsm:äitei/th

Schalin 2018: 84 "Pajusalu (2010) ... significantly affects the analysis of the loanword Fi äiti ‘mother’ < *äitei ← PSc *aiðijōn > ON eiða ~ Runic OESc obl. aiþu. In the light of the data in Pajusalu (2010: 330, 332) there must have existed a South-Estonian cognate to the Finnish word. The match is exact to the extent that the retained stem vowel, much like some Finnish dialects, indicates a long LPFc vowel, or diphthong *äitei, which is highly unusual and thus original. The reconstruction is supported by the Leivu dialect in an exclave in Latvia, with the attested form äid′ie."

Pajusalu, K. (2010). Äidin nimityksiä viron murteissa. In S. Saarinen, K. Siitonen, & T. Vaittinen (Eds.), Sanoista kirjakieliin: juhlakirja Kaisa Häkkiselle 17. marraskuuta 2010 (pp. 329–334). Helsinki: Suomalais-Ugrilainen Seura.

Schalin, J (2018): Preliterary Scandinavian sound change viewed from the east. Umlaut remodelledand language contacty revisited. Doctoral complilation thesis (summary chapter).Helsinki–Helsingfors (Nordica Helsingiensia 54). http://urn.fi/URN:ISBN:978-951-51-4387-7