worm - any of numerous relatively small elongated soft-bodied animals especially of the phyla Annelida and Chaetognatha and Nematoda and Nemertea and Platyhelminthes; also many insect larvae

Annelida, phylum Annelida - segmented worms: earthworms; lugworms; leeches

archiannelid - small primitive marine worm lacking external segmentation and resembling polychaete larvae

oligochaete, oligochaete worm - hermaphroditic terrestrial and aquatic annelids having bristles borne singly along the length of the body

polychaete, polychaete worm, polychete, polychete worm - chiefly marine annelids possessing both sexes and having paired appendages (parapodia) bearing bristles

bloodsucker, hirudinean, leech - carnivorous or bloodsucking aquatic or terrestrial worms typically having a sucker at each end

zoological science, zoology - the branch of biology that studies animals