Apocrypha are works, usually written works, that are of unknown authorship, or of doubtful origin. In the context of the Jewish and Christian Bibles, where some texts are of unknown authorship, Apocrypha usually is used by Protestants to refer to a set of texts included in the Septuagint and therefore included in the Catholic canon, but not in the Hebrew Bible.
The word’s origin is the Medieval Latin adjective apocryphus, “secret, or non-canonical”, from the Greek adjective ἀπόκρυφος (apokryphos), “obscure”, from the verb ἀποκρύπτειν (apokryptein), “to hide away”.
“We have found this information to be very important to us. It deals with Prophecy that pertains to the seed of Jacob’s People. You will know what will become of Jacob’s Children dealing with Esau’s Descendants.” 2 Esdras chapter 6:8.9