The Collaborative International Dictionary of English v.0.48:

Decease \De*cease"\, v. i. [imp. & p. p. Deceased; p. pr. &
   vb. n. Deceasing.]
   To depart from this life; to die; to pass away.
   [1913 Webster]

         She's dead, deceased, she's dead.        --Shak.
   [1913 Webster]

         When our summers have deceased.          --Tennyson.
   [1913 Webster]

         Inasmuch as he carries the malignity and the lie with
         him, he so far deceases from nature.     --Emerson.
   [1913 Webster]