noun

flatworm

FLAT-wurm

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Flatworm (noun) means any of the many parasitic or free-living worms of the phylum Platyhelminthes, with a flattened body and no skeleton or body cavity. Example: “Some flatworms live freely in ponds and streams, while others are parasites.”

noun

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

"Some flatworms live freely in ponds and streams, while others are parasites."

"A flatworm's body is flattened from top to bottom rather than round like an earthworm's."

"Parasitic flatworms can live inside the bodies of other animals."

How to use flatworm

Learner’s notes

In plain EnglishA worm with a flat, ribbon-like body and no internal body cavity.

When to use it

It is a plain biological term used in both everyday and scientific writing.

Memory tip

The name describes the worm's flattened shape, which sets it apart from round worms like earthworms.

Trace the full origin ↓

Easily confused with

roundworm

Common pairings

a parasitic flatworm free-living flatworms a flatworm species flatworm anatomy

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C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

Test yourself on “flatworm” A quick quiz — meaning, synonyms & usage →

Fill the gap

Can you complete this real example?

Some _____ live freely in ponds and streams, while others are parasites.

Etymology

Flatworm combines flat and worm, and the word was formed as a calque, or direct translation, of the scientific name Platyhelminthes.

Origin: English

Synonyms

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platyhelminth

Frequently asked questions

What is a flatworm?

It is any of a large group of worms in the phylum Platyhelminthes that have a flattened body and lack a skeleton or internal body cavity.

Are all flatworms parasites?

No, some flatworms live freely in water or damp habitats, while others live as parasites inside other animals.

What phylum do flatworms belong to?

They belong to the phylum Platyhelminthes, and the common name flatworm is a direct translation of that scientific name.

What is the meaning of flatworm?

"flatworm" (noun) means any of the many parasitic or free-living worms of the phylum Platyhelminthes, with a flattened body and no skeleton or body cavity.