The Collaborative International Dictionary of English v.0.48:

Demise \De*mise"\, n. [F. d['e]mettre, p. p. d['e]mis,
   d['e]mise, to put away, lay down; pref. d['e]- (L. de or
   dis-) + mettre to put, place, lay, fr. L. mittere to send.
   See Mission, and cf. Dismiss, Demit.]
   1. Transmission by formal act or conveyance to an heir or
      successor; transference; especially, the transfer or
      transmission of the crown or royal authority to a
      successor.
      [1913 Webster]

   2. The decease of a royal or princely person; hence, also,
      the death of any illustrious person.
      [1913 Webster]

            After the demise of the Queen [of George II.], in
            1737, they [drawing- rooms] were held but twice a
            week.                                 --P.
                                                  Cunningham.
      [1913 Webster]

   3. (Law) The conveyance or transfer of an estate, either in
      fee for life or for years, most commonly the latter.
      --Bouvier.
      [1913 Webster]

   Note: The demise of the crown is a transfer of the crown,
         royal authority, or kingdom, to a successor. Thus, when
         Edward IV. was driven from his throne for a few months
         by the house of Lancaster, this temporary transfer of
         his dignity was called a demise. Thus the natural death
         of a king or queen came to be denominated a demise, as
         by that event the crown is transferred to a successor.
         --Blackstone.
         [1913 Webster]

   Demise and redemise, a conveyance where there are mutual
      leases made from one to another of the same land, or
      something out of it.

   Syn: Death; decease; departure. See Death.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Demise \De*mise"\, v. t. [imp. & p. p. Demised; p. pr. & vb.
   n. Demising.]
   1. To transfer or transmit by succession or inheritance; to
      grant or bestow by will; to bequeath. "Power to demise my
      lands." --Swift.
      [1913 Webster]

            What honor
            Canst thou demise to any child of mine? --Shak.
      [1913 Webster]

   2. To convey; to give. [R.]
      [1913 Webster]

            His soul is at his conception demised to him.
                                                  --Hammond.
      [1913 Webster]

   3. (Law) To convey, as an estate, by lease; to lease.
      [1913 Webster]

WordNet (r) 3.0 (2006):

demise
    n 1: the time when something ends; "it was the death of all his
         plans"; "a dying of old hopes" [syn: death, dying,
         demise] [ant: birth]
    v 1: transfer by a lease or by a will