Source : Webster's Revised Unabridged Dictionary (1913)

Broccoli \Broc"co*li\, n. [It. broccoli, pl. of broccolo sprout,
   cabbage sprout, dim. of brocco splinter. See {Broach}, n.]
   (Bot.)
   A plant of the Cabbage species ({Brassica oleracea}) of many
   varieties, resembling the cauliflower. The ``curd,'' or
   flowering head, is the part used for food.

Source : WordNet®

broccoli
     n 1: plant with dense clusters of tight green flower buds [syn: {Brassica
          oleracea italica}]
     2: branched green undeveloped flower heads