The Slavic autonym is reconstructed in Proto-Slavic as *Slovenin, plural *Slovene. The oldest documents written in Old Church Slavonic and dating from the 9th century attest Slovene to describe the Slavs. Other early Slavic attestations include Old East Slavic Slovene for "an East Slavic group near Novgorod." However, the earliest written references to the Slavs under this name are in other languages. In the 6th century AD Procopius, writing in Byzantine Greek, refers to the Sklaboi, Sklabenoi, Sklauenoi, Sthlabenoi, or Sklabinoi, while his contemporary Jordanes refers to the Sclaveni in Latin.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): Procopius' contemporary Jordanes referred to the Slavs in what language?
Latin