Source : Webster's Revised Unabridged Dictionary (1913)

Water lemon \Wa"ter lem"on\ (Bot.)
   The edible fruit of two species of passion flower
   ({Passiflora laurifolia}, and {P. maliformis}); -- so called
   in the West Indies.

Source : WordNet®

Passiflora laurifolia
     n : West Indian passionflower; cultivated for its yellow edible
         fruit [syn: {Jamaica honeysuckle}, {yellow granadilla}]