The Collaborative International Dictionary of English v.0.48:

Testament \Tes"ta*ment\, n. [F., fr. L. testamentum, fr. testari
   to be a witness, to make one's last will, akin to testis a
   witness. Cf. Intestate, Testify.]
   1. (Law) A solemn, authentic instrument in writing, by which
      a person declares his will as to disposal of his estate
      and effects after his death.
      [1913 Webster]

   Note: This is otherwise called a will, and sometimes a last
         will and testament. A testament, to be valid, must be
         made by a person of sound mind; and it must be executed
         and published in due form of law. A man, in certain
         cases, may make a valid will by word of mouth only. See
         Nuncupative will, under Nuncupative.
         [1913 Webster]

   2. One of the two distinct revelations of God's purposes
      toward man; a covenant; also, one of the two general
      divisions of the canonical books of the sacred Scriptures,
      in which the covenants are respectively revealed; as, the
      Old Testament; the New Testament; -- often limited, in
      colloquial language, to the latter.
      [1913 Webster]

            He is the mediator of the new testament . . . for
            the redemption of the transgressions that were under
            the first testament.                  --Heb. ix. 15.
      [1913 Webster]

   Holographic testament, a testament written wholly by the
      testator himself. --Bouvier.
      [1913 Webster]

WordNet (r) 3.0 (2006):

testament
    n 1: a profession of belief; "he stated his political testament"
    2: a legal document declaring a person's wishes regarding the
       disposal of their property when they die [syn: will,
       testament]
    3: strong evidence for something; "his easy victory was a
       testament to his skill"
    4: either of the two main parts of the Christian Bible