The Collaborative International Dictionary of English v.0.48:

Jinnee \Jin"nee\, Jinni \Jin"ni\(j[i^]n"n[=e]), n.; pl. Jinn
   (j[i^]n). [Ar.] (Arabian & Mohammedan Myth.)
   A genius or demon; one of the fabled genii, good and evil
   spirits, supposed to be the children of fire, and to have the
   power of assuming various forms. [Written also djinnee,
   genie, etc.]

   Syn: jinn; jin; djinn.
        [1913 Webster]

   Note: Jinn is also used as sing., with pl. jinns.
         [1913 Webster]

WordNet (r) 3.0 (2006):

jinni
    n 1: (Islam) an invisible spirit mentioned in the Koran and
         believed by Muslims to inhabit the earth and influence
         mankind by appearing in the form of humans or animals [syn:
         genie, jinni, jinnee, djinni, djinny, djinn]

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "jinni":
   Baba Yaga, Lilith, afreet, barghest, cacodemon, daeva, demon,
   devil, dybbuk, evil genius, evil spirit, fiend, fiend from hell,
   genie, genius, ghoul, gyre, hellion, incubus, jinniyeh, lamia,
   rakshasa, satan, shedu, succubus, the undead, vampire, yogini