NOUN (3)

1. any of several night-blooming cacti of the genus Selenicereus;

2. any of several cacti of the genus Hylocereus;

3. any of several cacti of the genus Cereus;

The Collaborative International Dictionary of English v.0.48:

Night-blooming \Night"-bloom`ing\, a.
   Blooming in the night.
   [1913 Webster]

   Night-blooming cereus. (Bot.) See Note under Cereus.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cereus \Ce"re*us\, n. [L., a wax candle, fr. cera wax. So named
   from the resemblance of one species to the columnar shape of
   a wax candle.] (Bot.)
   A genus of plants of the Cactus family. They are natives of
   America, from California to Chili.
   [1913 Webster]

   Note: Although several species flower in the night, the name
         Night-blooming cereus is specially applied to the
         Cereus grandiflorus, which is cultivated for its
         beautiful, shortlived flowers. The Cereus giganteus,
         whose columnar trunk is sometimes sixty feet in height,
         is a striking feature of the scenery of New Mexico,
         Texas, etc.
         [1913 Webster]

WordNet (r) 3.0 (2006):

night-blooming cereus
    n 1: any of several night-blooming cacti of the genus
         Selenicereus
    2: any of several cacti of the genus Hylocereus
    3: any of several cacti of the genus Cereus