gaisas

Cognate with Latvian gàiss (“air, atmosphere, sky”); further origin outside of Baltic uncertain.^[1]

Beekes tentatively derives the word from Proto-Indo-European *gʷʰeh₂i-so- and connects Ancient Greek φαιός (phaiós, “(dark) gray, blackish”); this is formally acceptable, but the semantic link is rather tenuous.

Derksen tentatively rejects the above derivation, and espouses Fraenkel's traditional derivation from an unattested Lithuanian *gaid-sas, from Proto-Indo-European *gʷʰh₂eyd-, whence also giẽdras (“clear”), Ancient Greek φαιδρός (phaidrós, “bright, beaming”).

• IPA^(key):

gaĩsas m (plural gaisaĩ) stress pattern 4

1. glow, light, gleam
2. beam, ray
3. atmosphere

• “gaisas”, in Lietuvių kalbos žodynas [Dictionary of the Lithuanian language], lkz.lt, 1941–2024
• “gaisas”, in Lietuvių kalbos etimologinio žodyno duomenų bazė [Lithuanian etymological dictionary database], 2007–2012