The Collaborative International Dictionary of English v.0.48:

Ferocactus \Ferocactus\ n.
   a genus of nearly globular cacti of Mexico and Southwestern
   U. S., including some of the barrel cacti.

   Syn: genus Ferocactus.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Ferocactus
    n 1: genus of nearly globular cacti of Mexico and southwestern
         United States: barrel cacti [syn: Ferocactus, genus
         Ferocactus]