Usually explained as a borrowing from a Germanic language due to the voiceless centum reflex of the Proto-Indo-European palatovelar */ǵ/; compare the Proto-Germanic root noun *meluks (“milk”), itself from Proto-Indo-European *h₂melǵ- (“to milk”).
However, the Early Proto-Slavic form *melka- (> Late Proto-Slavic *melko) formally presents difficulties, because Slavic shows no trace of the *u in the Germanic second syllable. This would require an intermediary language that would drop the medial *-u- from Proto-Germanic word and thematicize the stem. In High German, forms lacking the second root syllable are attested only from Middle High German onwards, which is too late for it to be the donor of the Proto-Slavic form.
Other theories include:
- According to Valentin Kiparsky the Proto-Slavic *melko (“milk”) is completely separate from the reflexes of Proto-Germanic *meluks (“milk”), and instead derives from Proto-Slavic *molka (> Serbo-Croatian mlȁka/мла̏ка (“pool, puddle”), Old East Slavic молокита (molokita, “swamp”)). This etymology has been criticized as semantically far-fetched.
- According to Oleg Trubačev, Proto-Slavic *melko is unlikely to be a borrowing, among other reasons because it belongs to the accent paradigm b. However, this argument is weak since the final stress goes back to earlier stem stress, which is not unlikely among the Germanic loanwords in Proto-Slavic.
- Additional argument against Germanic origin is the neuter gender of the Slavic word, since loanwords rarely become neuter when they are borrowed into Proto-Slavic, and neuter donor words mainly become masculine or feminine.
Therefore, the exact origin cannot be specified. The etymology as a Germanic loanword is met with formal difficulties, while native origin is similarly complicated.
The same Proto-Indo-European root regularly gave Proto-Slavic *mьlsti (“to milk”), with a stem-final sibilant */s/. From the same Indo-European root are also Latin mulgeō, Ancient Greek ἀμέλγω (amélgō), Lithuanian mélžti, Welsh blith, Tocharian A malke.
- East Slavic:
- South Slavic:
- Derksen, Rick (2008) Etymological Dictionary of the Slavic Inherited Lexicon (Leiden Indo-European Etymological Dictionary Series; 4), Leiden, Boston: Brill, ISBN 978 90 04 15504 6, page 307
- Trubačev O. N., editor (1992), “*melko”, in Etimologičeskij slovarʹ slavjanskix jazykov [Etymological dictionary of Slavic languages] (in Russian), volume 18, Moscow: Nauka, page 84ff
- Saskia Pronk-Tiethoff (2013), The Germanic loanwords in Proto-Slavic, Rodopi: Amsterdam/New York, page 197f