Hungarian Historical Phonology füst
füst 'smoke; (old) steam, haze; Rauch; (alt.) Dampf, Dunst'
First attestation/Old Hungarian data
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1240 Fystpénz (compound)
See EWUng: 435, s.v. füst
Important dialectal forms
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Uralic/Pre-Hungarian reconstruction
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(Disputed:)
UEW: PUg *pičɜ (pićɜ) 'Rauch; smoke'
WOT: 1051, 1277: *pućə
Cognates suggested in earlier research
Khanty: North (O) posəŋ 'Rauch; Staub'
Mansi: North (So) posim, South (T) pošėm, West (P) pošəm 'Rauch; Staub'
Loan etymology
Hu füst ← Middle Iranian *pazda(ka)- (Helimski 2002)
Commentary
Hu füst cannot be regularly connected with the Ob-Ugric cognates listed in the UEW, as the vocalism is completely irregular (Khanty and Mansi o cannot correspond to Hungarian ü regularly). The reconstruction with *i is an ad hoc choice. It is also unclear what is the role of *-t here; according to UEW it is a derivational suffix, but nothing is said about its function. Also Helimski (2002) notes that the Ugric etymology is uncertain. Despite the problems, the Ugric etymology is found in the EWUng, and also WOT supports the idea of a Ugric etymology, reconstructing *pućə, but this is also an untenable proto-form for the words in the present Ugric languages. No additional arguments in favour of the Ugric etymology are presented in WOT.
Both UEW and Abondolo (1996) mention the possibility that the word-initial *p has influenced the development of Hu vocalism, but this is an ad hoc explanation.
The Khanty and Mansi words are probably somehow connected with each other but further research is needed.
Following Munkácsi (1901), Helimski (2002) assumes an Iranian origin for the Hungarian word, suggesting Middle Iranian *pazda(ka)- as the source. Helimski lists Sogdian pzt- (pazd-) and Ossetic (Iron) fæzdæg ‘Rauch’ as reflexes of this Iranian word. As a parallel to the substitution of *zd as Hu st, Helimski mentions the Iranian etymology of Hungarian isten 'God', which according to him is a loan from a Middle Iranian form akin to Middle Persian yazdān 'Gottheit'. This issue requires further research, but formally/phonetically it is a plausible idea that Iranian zd could be reflected as st in Hungarian, if the word was borrowed before a cluster zd was possible in Hungarian and s [š] already existed as a phoneme. It seems that this word should be then be an earlier loan than gazdag 'rich'.
The ü-vocalism is explained by Helimski as influence from the preceding labial consonant, similarly as in the case of üsző.
The Iranian etymology seems to be the most convincing possibility. It is difficult to determine whether the word has been borrowed from an Alanic form that already had *f (from Proto-Iranian *p) or if the word was borrowed before the similar change took place in Hungarian. In any case the word can not belong to the latest layer of Alanic loans in Hungarian, as zd would have been possible in this case.
The Hungarian word probably was not borrowed from a derived form like Ossetic fæzdæg but from a reflex of the underived noun *pazda'-, as there are not traces of the suffixal element in Hungarian.
Conclusion
The Ugric etymology is implausible. The Hungarian word is probably borrowed from Iranian *pazda-(ka-) (> Oss fæzdæg) as suggested by Helimski (2002), even if some phonological details require further research.
References
Abondolo 1996: 64: PUg
EWUng: 435, s.v. füst: PUg
Helimski 2002: Hu ← Ir
Rédei 1998/1999: PUg
UEW: PUg *pičɜ (pićɜ) Uralonet
WOT: 1051, 1277: PUg