Apocrypha are works, usually written works, that are of unknown authorship, or of doubtful authenticity, or spurious, or not considered to be within a particular canon. The word is properly treated as a plural, but in common usage is often singular. In the context of the Jewish and Christian Bibles, where most texts are of unknown authorship, Apocrypha usually refers to a set of texts included in the Septuagint but not in the Hebrew Bible.