The deuterocanonical books are the books that Catholicism and Eastern Orthodoxy include in the Old Testament that were not part of the Jewish Tanakh. The books are: Tobit (Tobias), Judith, 1 Maccabees, 2 Maccabees, Wisdom of Solomon, Sirach (Ecclesiasticus), and Letter of Baruch. The deuterocanonical material also includes additions to the books of Esther and Daniel. (See Apocrypha for more detail.)
Like Jews, most Protestants exclude these books as apocryphal. The word 'deuterocanonical' comes from the Greek for 'second canon'. The meaning of the name is a matter of dispute. Some hold that they are so called because they were written at a later time than the Jewish scriptures, and that they are included in the Old Testament because they were written before the time of Jesus. Others (see Catholic Encyclopedia entry cited in References) hold that the term merely serves to set off those books whose status has been a matter of dispute.
Most Septuagint manuscripts include the deuterocanonical books and passages. Like the New Testament, the deuterocanonical books were mostly written in Greek. Some were written in Hebrew, but the original text has long been lost and exists only in the ancient Greek translation. One, 2 Esdras, survives only in an ancient Latin translation but was probably composed in Greek.
Using the word "apocrypha" implies that the writings in question should not be included in the Bible, lumping them together with certain apocryphal gospels. The Style Manual for the Society of Biblical Literature recommends the use of the term "deuterocanonical literature" instead of "Apocrypha" in academic writing.