The Collaborative International Dictionary of English v.0.48:

Eryngium \E*ryn"gi*um\ ([-e]*r[i^]n"j[i^]*[u^]m), n. [NL., fr.
   Gr. 'hry`ggion, dim. of 'h`ryggos eryngo; cf. L. eryngion,
   erynge.] (Bot.)
   A large genus of umbelliferous plants somewhat like thistles
   in appearance, cosmopolitan in distribution. Eryngium
   maritimum, or sea holly, has been highly esteemed as an
   aphrodisiac, the roots being formerly candied.

   Syn: genus Eryngium.
        [1913 Webster]

WordNet (r) 3.0 (2006):

Eryngium
    n 1: large genus of decorative plants with thistlelike flower
         heads; cosmopolitan in distribution [syn: Eryngium,
         genus Eryngium]