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]