(Science: zoology) An order of worms, having a long, round, and generally smooth body; the roundworms. They are mostly parasites. Called also Nematodea, and nematoda.
The trichina, stomach worm, and pinworm of man belong to this group. See also vinegar eel, under Vinegar, and gapeworm.
Origin: NL, fr. Gr, thread.