The Collaborative International Dictionary of English v.0.48:

Obi \O"bi\, n. [Prob. of African origin.]
   1. A species of sorcery, probably of African origin,
      practiced among the negroes of the West Indies. [Written
      also obe and obeah.] --De Quincey. --B. Edwards.
      [1913 Webster]

   2. A charm or fetich. [West Indies] --B. Edwards.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Obeah \O*be"ah\ n.
   Same as Obi. -- a. Of or pertaining to obi; as, the obeah
   man. --B. Edwards.
   [1913 Webster]

WordNet (r) 3.0 (2006):

obeah
    n 1: (West Indies) followers of a religious system involving
         witchcraft and sorcery [syn: obeah, obi]
    2: a religious belief of African origin involving witchcraft and
       sorcery; practiced in parts of the West Indies and tropical
       Americas [syn: obeah, obi]