Source : Webster's Revised Unabridged Dictionary (1913)

Echinococcus \E*chi`no*coc"cus\, n. [NL., fr. Gr. ? hedgehog,
   sea urchin + ? grain, seed. 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.

Source : WordNet®

echinococcus
     n : tapeworms whose larvae are parasitic in humans and domestic
         animals
     [also: {echinococci} (pl)]