Reconstruction:Proto-Slavic/-ъ

• *-ь (soft declension)

Since mid-19th century two scenarios for the development of Indo-European *-os in Slavic have been proposed, respectively deriving this desinence:

• immediately from Proto-Indo-European *-os with narrowing of the vowel in the final syllable.
• from the accusative, analogically after other stem classes (u- and i-stems), probably to avoid homonymy with the neuter ending *-o.

A variant of the former view first proposed by Zaliznyak, Dybo and Nikolayev holds that IE *-os became *-ə in Slavic, which developed into *-ъ in mainstream dialects but into -е (-e) in Old Novgorodian. In the latter view, the Old Novgorodian ending can be considered original, with generalisation of the front variant from the soft declension.

Some authors also speculated that *-os could have had both outcomes depending on some other factors, with subsequent generalisation of one or the other in different grammatical categories.

• *-ə

*-ъ m

1. (diachronic) Nominative singular desinence for masculine o-stems.
2. (synchronic) Deverbative, in combination with o-grade of the root, forming nouns of the form *-CoC-ъ.

   *poteťi (“to elapse; start flowing”) → *potokъ (“brook, stream”)

   *teťi (“to flow (liquid); run (time) etc.”) → *tokъ (“flow, stream”)

   *gňiti (“to rot”) → *gnojь (“pus”)

   *vesti (“to drive, take, carry”) → *vozъ (“cart, wagon”)

• Usually verbs ending in -V- change: i→oj, u/y→ov/av (for a/ě see *-sъ/*-xъ, *-mę)

• *-o (“ending for hypocoristic masculine names”) (argued to be the "real" reflex of PIE *-os)

• East Slavic:
  • Old East Slavic: -ъ (-ŭ)
• South Slavic:
  • Old Church Slavonic:

    Cyrillic: -ъ (-ŭ)

    Glagolitic: -ⱏ (-ŭ)

Widely agreed to have been inherited from Proto-Indo-European *-om, itself composed from the thematic vowel *-o- and the accusative singular ending *-m. A small minority of researches instead argued for an extension of the u-stem ending.

*-ъ

1. Accusative singular desinence for masculine o-stems

• East Slavic:
  • Old East Slavic: -ъ (-ŭ)
  • Old Novgorodian: -ъ (-ŭ)
• South Slavic:
  • Old Church Slavonic:

    Cyrillic: -ъ (-ŭ)

    Glagolitic: -ⱏ (-ŭ)

From Proto-Indo-European *-us, itself composed from the final vowel of the stem and the nominative singular ending *-s.

*-ъ

1. Nominative singular desinence for masculine u-stems

• East Slavic:
  • Old East Slavic: -ъ (-ŭ)
  • Old Novgorodian: -ъ (-ŭ)
• South Slavic:
  • Old Church Slavonic:

    Cyrillic: -ъ (-ŭ)

    Glagolitic: -ⱏ (-ŭ)

From Proto-Indo-European *-um, itself composed from the final vowel of the stem and the accusative singular ending *-m.

*-ъ

1. Accusative singular desinence for masculine u-stems

• East Slavic:
  • Old East Slavic: -ъ (-ŭ)
  • Old Novgorodian: -ъ (-ŭ)
• South Slavic:
  • Old Church Slavonic:

    Cyrillic: -ъ (-ŭ)

    Glagolitic: -ⱏ (-ŭ)

Two sources have been proposed, depending on the reconstruction of the Indo-European ending:

• Proto-Indo-European *-ōm or *-oHom with some kind of shortening.
• Proto-Indo-European *-om, the supposed athematic genitive plural alongside thematic *-ōm < *-o-om. A variant of this view holds that also thematic stems had *-om without the thematic vowel in Proto-Indo-European.

Proponents of the former view have sometimes connected the neocircumflex intonation in Slovene, the stem short vowel in Czech and the Serbo-Croatian desinence -ā with the alleged Proto-Slavic length.

*-ъ

1. Genitive plural desinence for hard stems of all classes.

• East Slavic:
  • Old East Slavic: -ъ (-ŭ)
  • Old Novgorodian: -ъ (-ŭ)
• South Slavic:
  • Old Church Slavonic:

    Cyrillic: -ъ (-ŭ)

    Glagolitic: -ⱏ (-ŭ)

• Vermeer, Willem (1991), “The mysterious North Russian nominative singular ending -е and the problem of the reflex of Indo-European *-os in Slavic”, in Die Welt der Slaven, volume 36, pages 271-295
• Olander, Thomas (2015) Proto-Slavic Inflectional Morphology: A Comparative Handbook, Leiden/Boston: Brill, →ISBN