The Collaborative International Dictionary of English v.0.48:

Cardoon \Car*doon"\ (k[aum]r*d[=oo]n"), n. [F. cardon. The same
   word as F. cardon thistle, fr. L. carduus, cardus, LL. cardo.
   See 3d Card.] (Bot.)
   A large herbaceous plant (Cynara Cardunculus) related to
   the artichoke; -- used in cookery and as a salad.
   [1913 Webster] cardsharp

WordNet (r) 3.0 (2006):

Cynara cardunculus
    n 1: southern European plant having spiny leaves and purple
         flowers cultivated for its edible leafstalks and roots
         [syn: cardoon, Cynara cardunculus]