Worms vs. Flatworm — What's the Difference?

Plural of worm

The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, platy, meaning "flat" and ἕλμινς (root: ἑλμινθ-), helminth-, meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion.

Any of various parasitic and nonparasitic worms of the phylum Platyhelminthes, such as a tapeworm or a planarian, characteristically having a soft, flat, bilaterally symmetrical body and no body cavity. Also called platyhelminth.

Any of very many parasitic or free-living worms, of the phylum Platyhelminthes, having a flattened body with no skeleton or body cavity.

Any worm belonging to the Platyhelminthes; also, sometimes applied to the planarians.

Parasitic or free-living worms having a flattened body