The Collaborative International Dictionary of English v.0.48:

Testamentary \Tes`ta*men"ta*ry\, a. [L. testamentarius: cf. F.
   testamentaire.]
   1. Of or pertaining to a will, or testament; as, letters
      testamentary.
      [1913 Webster]

   2. Bequeathed by will; given by testament.
      [1913 Webster]

            How many testamentary charities have been defeated
            by the negligence or fraud of executors!
                                                  --Atterbury.
      [1913 Webster]

   3. Done, appointed by, or founded on, a testament, or will;
      as, a testamentary guardian of a minor, who may be
      appointed by the will of a father to act in that capacity
      until the child becomes of age.
      [1913 Webster]

WordNet (r) 3.0 (2006):

testamentary
    adj 1: of or relating to a will or testament or bequeathed by a
           will or testament