Old East Slavic
- (historical) A Slavic language used from the 10th to the 14th centuries by East Slavs in the state of Kievan Rus and its successors. The ancestor of Belarusian, Russian, Rusyn and Ukrainian.
- Old East Slavonic
- Old Russian (refers to both Rus and Russia)
- Old Ukrainian (specific to Ukrainian or dialects different from common OES)
- Old Belarusian (specific to Belarusian or dialects different from common OES)