The Collaborative International Dictionary of English v.0.48:

Echinococcus \E*chi`no*coc"cus\ ([e^]*k[imac]"n[-o]*k[o^]k*k),
   n. [NL., fr. Gr. 'echi^nos hedgehog, sea urchin + ko`kkos
   grain, seed, berry. So called because forming little granular
   bodies, each armed with hooklets and disposed upon the inner
   wall of the hydatid cysts.] (Zo["o]l.)
   A parasite of man and of many domestic and wild animals,
   forming compound cysts or tumors (called hydatid cysts) in
   various organs, but especially in the liver and lungs, which
   often cause death. It is the larval stage of the T[ae]nia
   echinococcus, a small tapeworm peculiar to the dog. The
   adult form is not found in man.
   [1913 Webster]

WordNet (r) 3.0 (2006):

echinococcus
    n 1: tapeworms whose larvae are parasitic in humans and domestic
         animals