Old Church Slavonic око

← Proto-Balto-Slavic *ak- (derived)

← Proto-Indo-European *h₃ekʷ- (root)

← Proto-Indo-European *h₃ekʷ- (derived)

← Proto-Slavic *ȍko (inherited)

→ English eye (cognate)

→ Latvian aka (cognate)

→ Latvian acs (cognate)

→ Old Norse auga (cognate)

→ Russian воочию (mention)