Parasitic flatworms (including flukes)

Wikipedia Word definitions in Wikipedia
Trematoda is a class within the phylum Platyhelminthes . It includes two groups of parasitic flatworms , known as flukes . They are internal parasites of molluscs and vertebrates . Most trematodes have a complex life cycle with at least two hosts. The primary ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Trematodea \Trem`a*to"de*a\, n. pl. [NL., from Gr. ? having holes, from ?, ?, a hole.] (Zo["o]l.) An extensive order of parasitic worms. They are found in the internal cavities of animals belonging to all classes. Many species are found, also, on the gills ...