From Proto-Balto-Slavic *auˀis, from Proto-Indo-European *h₂éwh₂os (“grandfather”).
Cognates include Old Prussian awis (“uncle”); Russian уй (uj), Serbo-Croatian ујак, ujak < Proto-Slavic *ujь (“maternal uncle”), etc.
The suffix -ýnas is of unclear formation. It may be linked to the identical suffix in seserýnas (“relative on the sister's side”), brolýnas (“relative on the brother's side”). Compare also Bulgarian у́йна (újna, “aunt, uncle's wife”), Russian dialectal дя́д-ина (djád-ina, “uncle's wife”).
Further -n- extensions to the root *h₂ewh₂- can be found in Latin avunculus (“maternal uncle”), Breton eontr (“uncle”), Welsh ewythr (“uncle”).
avýnas m stress pattern 1
| singular (vienaskaita) | plural (daugiskaita) | |
|---|---|---|
| nominative (vardininkas) | avýnas | avýnai |
| genitive (kilmininkas) | avýno | avýnų |
| dative (naudininkas) | avýnui | avýnams |
| accusative (galininkas) | avýną | avýnus |
| instrumental (įnagininkas) | avýnu | avýnais |
| locative (vietininkas) | avýne | avýnuose |
| vocative (šauksmininkas) | avýne | avýnai |