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

class Trematoda, Trematoda - parasitic flatworms (including flukes)

Cestoda, class Cestoda - tapeworms

Aschelminthes, Nematoda, phylum Aschelminthes, phylum Nematoda - unsegmented worms: roundworms; threadworms; eelworms