A language, such as Latin, that is no longer learned as a native language by a speech community.
A language which no longer has any native speakers.
A more subtle danger to which we are especially liable in the case of a dead language is that of our acquiescing in a sense which satisfies us but which would not have satisfied the ancient writer.
He lifted a small soul-tracking device off the table, a round compass whose edges were lined with symbols from a dead language too old for him to read.
It would seem that up to the 4th century of our era the Sinhalese had written exclusively in their own tongue; that is to say that for six centuries they had studied and understood Pali as a dead language without using it as a means of literary expression.
The gradual replacement of Syriac by Arabic as the vernacular language of Mesopotamia by degrees transformed the Syriac from a living to a dead language.
Bembo, Sadoleto and the rest write purely in a dead language.