An apocryphal book, an early Christian epistle included in the biblical Codex Alexandrinus (late 4th century), the later Codex Hierosolymitanus which includes the Didache (1056). There is also a Syriac version. It cites "the prophetic word," otherwise unknown, and the apocryphal Gospel of the Egyptians.
It's a sermon on self-control, repentance, and judgment.
(The Anchor Bible Dictionary by Robert M. Grant, Volume 1, Page 1061) http://www.earlychristianwritings.com/2clement.html, https://symeon-anthony.info/BibleCanon/Alexandrinus/CodexAlexandrinus.html, http://www.ntcanon.org/codex_Hierosolymitanus.shtml)
Etymology of the Bible
The earliest Christian use of ta biblia (the books, the Bible) is maybe 2 Clement 2:14 (circa A.D. 150): "The books and the apostles declare that the church...has existed from the beginning."
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Page 3.)