Noun | 1. | ![]() flame cell - organ of excretion in flatworms 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 phylum Platyhelminthes, Platyhelminthes - flatworms planaria, planarian - free-swimming mostly freshwater flatworms; popular in laboratory studies for the ability to regenerate lost parts trematode, trematode worm, fluke - parasitic flatworms having external suckers for attaching to a host |