1. a cactus of the genus Ferocactus: unbranched barrel-shaped cactus having deep ribs with numerous spines and usually large funnel-shaped flowers followed by dry fruits • Hypernyms: cactus • Member Holonyms: Ferocactus, genus Ferocactus 2. any cactus of the genus Echinocactus; strongly ribbed and very spiny; southwestern United States to Brazil • Syn: echinocactus • Hypernyms: cactus • Hyponyms: hedgehog cactus, golden barrel cactus, Echinocactus grusonii • Member Holonyms: genus Echinocactus