Etymology
1. Disputed:
2. Traditionally derived from Proto-Baltic *putnas, a morphological variant of *putā- (originally “young bird”), from Proto-Indo-European *pōw-t-, *pu(h₂)-t- (“small one, baby”), from or akin to the root *pe(h₂)w- (“little”). Another possibility is that the original stem was *pawt- (“to father”), with Latvian pauts (“testicle”) (dialectally also “egg”) as a direct reflex; from the zero grade form *put- > putns (perhaps with the suffix -ens); in this respect, cf. Sudovian paud (“bird”). For these hypotheses, cognates include Lithuanian putýtis (“chick”), paũkštis (“bird”), Old Church Slavonic пътица (pŭtica), Russian пти́ца (ptíca), Sanskrit पोत (póta, “young animal, offspring”), पुत्र (putrá, “son, child”), Ancient Greek πῶλος (pôlos, “foal”), Latin puer (“child, boy”). Neither hypothesis, however, completely explains the form of this word.
3. A more recent suggestion is Proto-Indo-European *pet-, *peth₂- (“to jump, to fly, to fall”), from which Old Irish ēn (“bird”) (< *pet-no-), German Feder (“feather”) (< *pet-er-), Hittite 𒁁𒋻 (pát-tar, “wing”), Sanskrit पतति (patati, “to fly, to fall”), Ancient Greek πέτομαι (pétomai, “to fly”), πτερόν (pterón, “wing”), Latin penna (“feather”) (< *pet-na). From *pét-r-, *pet-n-és > *ptér-, *pten-és, where an epenthetic -u- would lead to *putne-, *puten- (cf. dialectal diminutive puteniņš with e), from which putns. See: Ancient Greek Nouns '
πῶλος', Latin Nouns '
puer', German Nouns '
Feder', Latin Nouns '
penna'.