Nemathelminthes \Nem`a*thel*min"thes\, Nematelminthes \Nem`a*tel*min"thes\, prop. n. pl. [NL. See {Nemato-}, and {Helminthes}.] (Zool.) An order of helminths, including the {Nematoidea} and Gordiacea; the roundworms. [Written also {Nematelminthea}.] [1913 Webster]