Heidegger's Bible Handbook: OT Apocrypha: The Term "Apocryphal"

2.  Whence are they called Apocryphal?  The answer to the נגנוזים/hidden books of the Hebrews.  The הארון/κιβωτὸς/ark of the Jews.

These books take their name from the Greek term Ἀπόκρυφοι/ Apocryphal, either because they are αἱ Βίβλοι ἀπὸ τῆς κρύπτης, books from the crypts/vaults (that is, cases, little arks, in which the Divine books were wont of old to be stored by the people of God, whence Tertullian[1] mentions the armarium Judaicum, Jewish book-crypt,[2] and Ephiphanius[3] the Ἀρὼν [הארון] καὶ τῆς διαθήκης κιβωτὸν, הארון and ark of the Testament, in his de Ponderibus et mensuris):  or because their authors were Ἀπόκρυφοι/hidden, that is, uncertain, which account of the name, in the judgment of Andradius[4] some have accounted altogether inept:  or because they were not of old δημοσιευόμενοι, common, made public, in the Church, or not read in it publicly for the proof of the doctrines of faith and life, which concerning the Greek Church Cyril of Jerusalem[5] acknowledges in his Catechesi:  or because of their authority was obscure and uncertain, and so they, as laboring under defect, as Ἀποκρυφῆς μᾶλλον ἢ ἀναγνώσεως ἄξιοι, worthy of a hiding-place rather than reading, as Saint Athanasius[6] speaks in his Synopsi, ought ἀποκρύπτεσθαι, to be hidden, to be kept privately, not ἐκκλησιάζεσθαι, to be brought into the Church, as the public canon of faith and life, but rather to be rejected from public and authentic use in the Church.  Which last etymological derivation is much closer to the truth.  For the Greek term Ἀπόκρυφος/Apocryphos corresponds with the Hebrew term גנוז/hidden.  Now, to the Hebrews the books נגנוזים/ Ἀπόκρυφοι/hidden are those that, written either defectively, or erroneously, and so by the human spirit, ought either to be reserved only for private uses, or even to be completely consigned to oblivion, and to be buried in the earth, lest they be able to be read by others, or any be able to be led into error through the reading of them.  Whence in the writings of the Hebrews the oft repeated formula occurs:  בקשו לגנוז, they (the Rabbis) wanted ἀποκρύπτειν, to hide, them, that is, to refer them to the number of the Apocryphal Books.

[1] Tertullian was a Latin Father of the second century.  He labored as an apologist during times of persecution.  He is remembered for his contribution of the vocabulary concerning the doctrine of the Trinity in the Latin-speaking West, and his involvement in the Montanist movement.

[2] On the Apparel of Women, chapter 3.

[3] The profound erudition of Epiphanius (c. 310-403) led to his installation as Bishop of Salamis.  He was something of a heresy hunter, combating Apollinarianism, Origen, and even at one point Chrysostom.

[4] Diogo de Paiva de Andrade (1528-1575) was a Portuguese theologian.  He was active at Trent, and afterwards, against the Protestant Reformation.

[5] Cyril of Jerusalem (315-386) was elected Bishop of Jerusalem in 350.  Cyril was a significant early theologian, and he is remembered for his Catechetical Lectures.

[6] Athanasius (c. 298-373) was bishop of Alexandria, and a great defender of Nicean orthodoxy.