The Collaborative International Dictionary of English v.0.48:

Ornithopoda \Or`ni*thop"o*da\, prop. n. pl. [NL. See Ornitho-,
   and -poda.] (Paleon.)
   An order of herbivorous dinosaurs with birdlike
   characteristics in the skeleton, esp. in the pelvis and hind
   legs, which in some genera had only three functional toes,
   and supported the body in walking as in Iguanodon. See
   Illust. in Appendix.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Ornithopoda
    n 1: widespread group including duck-billed dinosaurs and their
         early relatives (hadrosaurs, trachodon and iguanodon) [syn:
         Euronithopoda, suborder Euronithopoda, euronithopod,
         Ornithopoda, suborder Ornithopoda]