The Collaborative International Dictionary of English v.0.48:

Apocrypha \A*poc"ry*pha\, n. pl., but often used as sing. with
   pl. Apocryphas. [L. apocryphus apocryphal, Gr. ? hidden,
   spurious, fr. ? to hide; ? from + ? to hide.]
   1. Something, as a writing, that is of doubtful authorship or
      authority; -- formerly used also adjectively. [Obs.]
      --Locke.
      [1913 Webster]

   2. Specif.: Certain writings which are received by some
      Christians as an authentic part of the Holy Scriptures,
      but are rejected by others.
      [1913 Webster]

   Note: Fourteen such writings, or books, formed part of the
         Septuagint, but not of the Hebrew canon recognized by
         the Jews of Palestine. The Council of Trent included
         all but three of these in the canon of inspired books
         having equal authority. The German and English
         Reformers grouped them in their Bibles under the title
         Apocrypha, as not having dogmatic authority, but being
         profitable for instruction. The Apocrypha is now
         commonly ?mitted from the King James's Bible.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Apocrypha
    n 1: 14 books of the Old Testament included in the Vulgate
         (except for II Esdras) but omitted in Jewish and Protestant
         versions of the Bible; eastern Christian churches (except
         the Coptic Church) accept all these books as canonical; the
         Russian Orthodox Church accepts these texts as divinely
         inspired but does not grant them the same status

Easton's 1897 Bible Dictionary:

Apocrypha
   hidden, spurious, the name given to certain ancient books which
   found a place in the LXX. and Latin Vulgate versions of the Old
   Testament, and were appended to all the great translations made
   from them in the sixteenth century, but which have no claim to
   be regarded as in any sense parts of the inspired Word.

     (1.) They are not once quoted by the New Testament writers,
   who frequently quote from the LXX. Our Lord and his apostles
   confirmed by their authority the ordinary Jewish canon, which
   was the same in all respects as we now have it.

     (2.) These books were written not in Hebrew but in Greek, and
   during the "period of silence," from the time of Malachi, after
   which oracles and direct revelations from God ceased till the
   Christian era.

     (3.) The contents of the books themselves show that they were
   no part of Scripture. The Old Testament Apocrypha consists of
   fourteen books, the chief of which are the Books of the
   Maccabees (q.v.), the Books of Esdras, the Book of Wisdom, the
   Book of Baruch, the Book of Esther, Ecclesiasticus, Tobit,
   Judith, etc.

     The New Testament Apocrypha consists of a very extensive
   literature, which bears distinct evidences of its non-apostolic
   origin, and is utterly unworthy of regard.


Hitchcock's Bible Names Dictionary (late 1800's):

Apocrypha, hidden