It's a funny word. A root noun, originally, hence the dual *oc^-i (<
*okW-i: < *h3okW-ih1, cf. Gk. osse < *ok-je), and a Slavic *-es-stem
in the singular/plural (a consonantal neuter with a final *-kW was
phonotactically too awkward to survive).
The same behaviour can be seen in the "ear" word (sg. and pl. *ux-es-
, but du. *us^-i). Eyes and ears go together, so to speak, in many
languages.
Other groups show different developments of the consonantal stem,
e.g. *okW-s- (with an *-s- extension) as in Sanskrit, or a nasal
("weak") stem, as in Germanic, or of course *-i-, as in Lithuanian.
Piotr
--- In cybalist@..., "Sergejus Tarasovas" <S.Tarasovas@...> wrote:
> One shoud avoid writing in haste. *oko has a consonantal stem
(*oko -
> *oc^ese). It is Lithuanian which seemes to transform -s-stem to -i-
> stem, so akytas (I'm not aware of the word) is a rather ambiguous
> example. Or what?
>
> Sergei