Hungarian Historical Phonology tej
tej 'milk'
First attestation/Old Hungarian data
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Important dialectal forms
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Uralic/Pre-Hungarian reconstruction
*täjV or täjə
Kümmel 2020: 253: *täjV
WOT: Ancient Hungarian *teyə
Cognates suggested in earlier research
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Loan etymology
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Commentary
The Iranian origin of Hungarian tej 'milk' is accepted by all sources, but different donor forms have been suggested. The traditional view (reflected by EWUng and WOT and also supported by Holopainen 2019: 288) connect the Hungarian word to the Ossetic verb dæjyn, dayun 'suck (breast)' (Bielmeier 1977: 140; Garnier et al. 2017: 298–299). Kümmel suggests an (unattested?) noun *daya- 'sucking' as the origin. Katz (2003: 193) suggests the Indo-Iranian noun *dhā́yas 'the act of nourishing' (> Sanskrit dhā́yas) as the origin. This is phonologically a totally plausible etymology, and it would be more probable for a Hungarian noun to be borrowed from an Indo-Iranian noun. The exact meaning 'milk' is not attested for *dhā́yas, but 'nourishing' and 'milk' are not far from each other. The noun *dhā́yas is derived from *dhayH- 'suck' (reflected also by Oss dæjyn, dayun; EWAia II: 776, 788)), so it seems quite probable that a meaning 'milk' can be reconstructed for the noun, even if that is not attested in Sanskrit. The suggestion by Katz (2003) is thus the most convincing so far.
Hungarian e points to *ä, rather than *e as reconstructed by WOT. The voiceless stop points to an old loan. The ä-substitution is found in numerous loans into Hungarian, but this subsitution is rarely found in early loans with wider distribution in Uralic.
Conclusion
Hu tej is borrowed from Indo-Iranian *dhā́yas 'nourishment; milk (?)'.
References
EWUng: 1495, s.v. tej: Hu ← Ir, cf. Oss dæjyn, dayun
Harmatta 1977: 171
Holopainen 2019: 288
Katz 2003: 193
Kümmel 2020: 253: Hu ← PIr or Common Ir *daya- 'sucking (?)'
Ligeti 1986: 147
Lushnikova 1990: 44
WOT 1336: Hu ← Alanic *däy