The Collaborative International Dictionary of English v.0.48:

fatwa \fat"wa\, fatwah \fat"wah\, n.
   Same as fetwah.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Fetwah \Fet"wah\, n. [Ar.]
   A written decision of a Turkish mufti some point of law; also
   applied to opinions by certain other Islamic religious
   authorities on points of Islamic law, such as in Iran. [Also
   spelled fatwah and fatwa.] --Whitworth.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

fatwa
    n 1: a ruling on a point of Islamic law that is given by a
         recognized authority