Definition: A "trematode worm" is a type of flatworm that is a parasite. This means it lives on or inside another animal (called the host) and gets its food from that host. Trematode worms have special parts called external suckers that help them attach to their host.
In more advanced contexts, you might discuss the life cycle of trematode worms, which can involve multiple hosts and complex stages, including eggs, larvae, and adult worms.
A trematode worm is a flatworm that lives as a parasite in other animals, using suckers to attach to its host.