By surface analysis, *sъ + *vora, further, related to *verti.
*sъvora f
singular | dual | plural | |
---|---|---|---|
nominative | *sъvora | *sъvorě | *sъvory |
genitive | *sъvory | *sъvoru | *sъvorъ |
dative | *sъvorě | *sъvorama | *sъvoramъ |
accusative | *sъvorǫ | *sъvorě | *sъvory |
instrumental | *sъvorojǫ, *sъvorǫ** | *sъvorama | *sъvorami |
locative | *sъvorě | *sъvoru | *sъvorasъ, *sъvoraxъ* |
vocative | *sъvoro | *sъvorě | *sъvory |
* -asъ is the expected Balto-Slavic form but is found only in some Old Czech documents; -axъ is found everywhere else and is formed by analogy with other locative plurals in -xъ.
** The second form occurs in languages that contract early across /j/ (e.g. Czech), while the first form occurs in languages that do not (e.g. Russian).