The Collaborative International Dictionary of English v.0.48:

Intestate \In*tes"tate\, a. [L. intestatus; pref. in- not +
   testatus, p. p. of testari to make a will: cf. F. intestat.
   See Testament.]
   [1913 Webster]
   1. Without having made a valid will; without a will; as, to
      die intestate. --Blackstone.
      [1913 Webster]

            Airy succeeders of intestate joys.    --Shak.
      [1913 Webster]

   2. Not devised or bequeathed; not disposed of by will; as, an
      intestate estate.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Intestate \In*tes"tate\, n. (Law)
   A person who dies without making a valid will. --Blackstone.
   [1913 Webster]

WordNet (r) 3.0 (2006):

intestate
    adj 1: having made no legally valid will before death or not
           disposed of by a legal will; "he died intestate";
           "intestate property" [ant: testate]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

INTESTATE. One who, having lawful power to make a will, has made none, or
one which is defective in form. In that case, he is said to die intestate,
and his estate descends to his heir at law. See Testate.
     2. This term comes from the Latin intestatus. Formerly, it was used in
France indiscriminately with de confess; that is, without confession. It was
regarded as a crime, on account of the omission of the deceased person to
give something to the church, and was punished by privation of burial in
consecrated ground. This omission, according to Fournel, Hist. des Avocats,
vol. 1, p. 116, could be repaired by making an ampliative testament in the
name of the deceased. See Vely, tom. 6, page 145; Henrion De Pansey,
Authorite Judiciare, 129 and note. Also, 3 Mod. Rep. 59, 60, for the Law of
Intestacy in England.