Nematode definition

Any of several slender, cylindrical worms of the group Nematoda, which some scientists consider to be a class of the aschelminths and others to be a separate phylum. Most nematodes are tiny and live in enormous numbers in water, soil, plants, and animals. They have a simple structure, with a long hollow gut separated from the body wall by a fluid-filled space. Several nematodes, such as pinworm, roundworm, filaria, and hookworm, are parasites on animals and humans and cause disease. One species, Caenorhabditis elegans (usually called C. elegans ), was one of the first animals to have its entire genome sequenced and is important in biological research as a model organism.

Any of a phylum (Nemata) of worms, often parasites of animals and plants, with long, cylindrical, unsegmented bodies and a heavy cuticle, as the hookworm or pinworm; roundworm.

Any of numerous worms of the phylum Nematoda, having unsegmented cylindrical bodies often narrowing at each end, and including free-living species that are abundant in soil and water, and species that are parasites of plants and animals, such as eelworms, pinworms, and hookworms.

Any of numerous worms of the phylum Nematoda, having unsegmented cylindrical bodies often narrowing at each end, and including free-living species that are abundant in soil and water, and species that are parasites of plants and animals, such as eelworms, pinworms, and hookworms.