The Collaborative International Dictionary of English v.0.48:

Houri \Hou"ri\, n.; pl. Houris. [Per. h[=u]r[imac],
   h[=u]r[=a], h[=u]r; akin to Ar. h[=u]r, pl. of ahwar
   beautiful-eyed, black-eyed.]
   A nymph of paradise; -- so called by the Mohammedans.
   [1913 Webster]

WordNet (r) 3.0 (2006):

houri
    n 1: a voluptuously beautiful young woman [syn: nymph,
         houri]
    2: (Islam) one of the dark-eyed virgins of perfect beauty
       believed to live with the blessed in Paradise

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "houri":
   Adonis, Aphrodite, Apollo, Apollo Belvedere, Aspasia, Astarte,
   Balder, Cleopatra, Delilah, Freya, Hebe, Hyperion, Jezebel,
   Messalina, Narcissus, Phryne, Thais, Venus, Venus de Milo,
   adventuress, courtesan, demimondaine, demimonde, demirep,
   femme fatale, harem girl, hetaera, odalisque, peri, seductress,
   temptress, the Graces, vamp, vampire



The Devil's Dictionary (1881-1906):

HOURI, n.  A comely female inhabiting the Mohammedan Paradise to make
things cheery for the good Mussulman, whose belief in her existence
marks a noble discontent with his earthly spouse, whom he denies a
soul.  By that good lady the Houris are said to be held in deficient
esteem.