*aiþį̄

Probably derived from *aiþaz, originally denoting a woman joined by a binding marital oath, hence ‘lawful wife, wedded woman’ and subsequently ‘mother’. Hansen (2017a: 209–11) reconstructs a Proto-Indo-European formation *h₁óy-ti-h₃n(h₂)- (‘the one endowed or charged with an oath’), a ti-stem from an o-grade form of root *h₁ey-, with the Hoffmann suffix (creates nouns and adjectives meaning ‘one who possesses, is characterized by, or is associated with X’), though the precise suffixal analysis remains uncertain. The semantic development is supported by Old English æw and its adjectival use in the sense ‘lawful, legitimate’ (Hansen 2017a: 209–11; Mezger 1959; Milanova 2020: 85). The traditional interpretation as a nursery formation is unlikely; unlike genuine Germanic nursery words such as *attô and*ammǭ, *aiþį̄ lacks the characteristic phonological structure of child-directed formations (Hansen 2017a: 210; Hansen 2018: 176–79, 181). Proto-Finnic *äitei is probably borrowed from Germanic (Kylstra et al. 2012: 429–30).