There are countless esoteric writings that were not accepted as Scripture while the Bible was being canonized. Sects differ on which books form the Bible.
There are Old Testament apocryphal books (some of which are Deutercanonical) and New Testament apocryphal books. Not all apocryphal books are in the Apocrypha.
Etymology
The Greek word means "hidden things," and when applied to books, it means those works that religious authorities wished to be concealed from the reading public.
Such books were thought to contain mysterious or secret lore, meaningful only to the initiate and were unsuitable for the ordinary reader. Of course, hidden or esoteric teachings were not part of the Hebrew tradition and entered from pagan sources and generally involved forbidden magical practices. The seeking the "hidden things" of Jesus ben Sirach and Ecclesiasticus means knowing the mind and will of God, not the esoteric treatises of Hellenistic authors.
It can also be applied in a less complimentary sense to works that deserved to be concealed due to their harmful doctrines or false teachings. At this time, only a few copies of any book were in circulation, and burning easily eliminated them so "hiding" seems unnecessary.
And a number of those who had practiced magic arts brought their books together and burned them in the sight of all. And they counted the value of them and found it came to fifty thousand pieces of silver. - Acts 19:19
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Old Testament and New Testament Apocrypha by R. K. Harrison, Page 83.)
Using "apocrypha" to mean "noncanonical" goes back to the 5th century A.D., when Jerome urged that the books that appear in the Septuagint and Latin Bibles but not the Hebrew Bible should be treated as apocryphal. They are not inspired and cannot be used for a source of Christian doctrine, but they are a valuable part of the great contemporary outpouring of Jewish national literature.
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Old Testament and New Testament Apocrypha by R. K. Harrison, Page 84.)