The Collaborative International Dictionary of English v.0.48:

Tanak \Tanak\, Tanakh \Tanakh\, n. [From the initial (Hebrew)
   letters of Torah, Nevi'im, and Kethubim.]
   a term used among Jews for the Hebrew Bible; the Old
   Testament. [Also spelled Tanach.]

   Note: Although Christians use the term "Old Testament", this
         term implies the superseding force of the "New
         Testament", not recognized as revelation by the Jewish
         faith.
         [PJC]

               The Hebrew Bible is divided into three parts: (1)
               The Torah, "Law," or Pentateuch. (2) The
               Prophets . . . (3) The Kethubim, or the
               "Writings," generally termed Hagiographa. --C.
                                                  H. H. Wright.
         [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Tanach
    n 1: the Jewish scriptures which consist of three divisions--the
         Torah and the Prophets and the Writings [syn: Tanakh,
         Tanach, Hebrew Scripture]

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

Tanach, same as Taanach