Circumflex on Lithuanian õ indicates a Proto-Indo-European long vowel (i.e. a lengthened grade) as the origin, as opposed to the short *e or *o with followed by a laryngeal.
According to the usual doctrine, the initial form was *h₁ōd, ablative singular of the PIE demonstrative pronoun *éy, h₁e. However, that demonstrative has no such ablative singular attested in any of the daughter languages, so that hypothesis remains unprovable.
The same PIE proto-form could have also yielded Sanskrit आत् (ā́t, “so, then, afterwards”) and Avestan 𐬁𐬀𐬝 (āat̰) ("afterwards, then").
- East Slavic:
- South Slavic:
- West Slavic:
- ^ E.g. Derksen 2008:25