Akademik

attestation
noun /ˈæ.tɛs.teɪ.ʃən/
a) Something which bears witness, confirms or authenticates

The poem called ‘Beowulf,’ preserved on the Nowell Codex, is one attestation of Old English, which can thus be called an ‘attested language’; Proto-Indo-European, a reconstructed language, has no such attestations.

b) Such a confirmation or authentication

Wikipedia foundation.