The Collaborative International Dictionary of English v.0.48:
Carduus \Carduus\ n. a genus of annual or perennial Old World prickly thistles. Syn: genus Carduus. [WordNet 1.5]WordNet (r) 3.0 (2006):
Carduus n 1: genus of annual or perennial Old World prickly thistles [syn: Carduus, genus Carduus]