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flatworm

/ˈflæt.wəɹm/noun

flatworm is a noun meaning “Any of very many parasitic or free-living worms, of the phylum Platyhelminthes, having a flattened body with no skeleton or body cavity” (English Wiktionary, September 2026). It is spelled F-L-A-T-W-O-R-M and has 2 syllables, and it appears about once in every 19 million words in written English (wordfreq, 2021 data). The plural of flatworm is flatworms.

What does flatworm mean?

noun

  1. 1

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

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

How do you pronounce flatworm?

  • US /ˈflæt.wəɹm/

Flatworm has 2 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vealhurl-flatworm.wav, Wikimedia Commons (author and licence on each file's page).

Forms of flatworm

  • flatworms plural

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).

How common is flatworm?

Flatworm appears about once in every 19 million words in written English, the 133,440th most frequent word form in the list.

Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).

Flatworm in Spanish, French, German and Portuguese

In the sense worm of Platyhelminthes:

LanguageWords
Frenchver plat
GermanPlattwurm
Portugueseplatelminto
Spanishplatelminto, gusano plano

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.

Where does flatworm come from?

From flat + worm, a calque of taxonomic name Platyhelminthes.

Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).