[1] : The Collaborative International Dictionary of English v.0.48

cereus \ce"reus\, 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
see also:
night-blooming cereus cereus grandiflorus cereus giganteus 

[2] : WordNet (r) 2.0

cereus
     n : genus of much-branched treelike or shrubby cacti with
         pronounced ribs and rounded needlelike spines and
         nocturnal flowers usually white syn: genus cereus
see also:
genus cereus 

Cereus >> C Words
Cereus, definition of term: Cereus
cereus_pag1.html

Cereus Grandifl >> C Words
Cereus Grandifl, definition of term: Cereus Grandifl
cereus+grandifl_pag1.html