The Collaborative International Dictionary of English v.0.48:

Granadilla \Gran`a*dil"la\, n. [Sp., dim. of granada
   pomegranate. See Grenade, Garnet.] (Bot.)
   The fruit of certain species of passion flower (esp.
   Passiflora quadrangularis) found in Brazil and the West
   Indies. It is as large as a child's head, and is a good
   dessert fruit. The fruit of Passiflora edulis is used for
   flavoring ices.
   [1913 Webster]

WordNet (r) 3.0 (2006):

granadilla
    n 1: tropical American passionflower yielding the large
         granadilla fruit [syn: granadilla, giant granadilla,
         Passiflora quadrangularis]
    2: considered best for fruit [syn: granadilla, sweet
       granadilla, Passiflora ligularis]
    3: Brazilian passionflower cultivated for its deep purple fruit
       [syn: granadilla, purple granadillo, Passiflora edulis]
    4: the egg-shaped edible fruit of tropical American vines
       related to passionflowers