The Collaborative International Dictionary of English v.0.48:

Helminthes \Hel*min"thes\, n. pl. [NL., fr. Gr. ?, ?, a worm.]
   (Zool.)
   One of the grand divisions or branches of the animal kingdom.
   It is a large group including a vast number of species, most
   of which are parasitic. Called also Enthelminthes,
   Enthelmintha.
   [1913 Webster]

   Note: The following classes are included, with others of less
         importance: Cestoidea (tapeworms), Trematodea (flukes,
         etc.), Turbellaria (planarians), Acanthocephala
         (thornheads), Nematoidea (roundworms, trichina,
         gordius), Nemertina (nemerteans). See Plathelminthes,
         and Nemathelminthes.
         [1913 Webster]