[ flat-wurm ]
/ ˈflætˌwɜrm /


any worm of the phylum Platyhelminthes, having bilateral symmetry and a soft, solid, usually flattened body, including the planarians, tapeworms, and trematodes; platyhelminth.

Origin of flatworm

First recorded in 1895–1900; flat1 + worm
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for flatworm

  • Such is seen in the life history of the liver fluke, a flatworm which kills sheep, and in the tapeworm.

    A Civic Biology|George William Hunter
  • If a flatworm be cut in two, the front piece grows out a new tail, the hind piece a new head, and two perfect worms result.

    Biology|Edmund Beecher Wilson
  • The parasite that's doing the damage is a flatworm, a trematode called Hepatodirus hominis.

    The Lani People|J. F. Bone

British Dictionary definitions for flatworm

/ (ˈflætˌwɜːm) /


any parasitic or free-living invertebrate of the phylum Platyhelminthes, including planarians, flukes, and tapeworms, having a flattened body with no circulatory system and only one opening to the intestine
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for flatworm

[ flătwûrm′ ]


Any of various worms of the phylum Platyhelminthes, including the parasitic tapeworms and flukes, characteristically having a soft, flat, bilaterally symmetrical body and no body cavity.platyhelminth
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for flatworm

[ flătwûrm′ ]

Any of various parasitic and nonparasitic worms of the phylum Platyhelminthes, characteristically having a soft, flat, bilaterally symmetrical body. Flatworms lack a coelom (body cavity), respiratory system, and circulatory system, but are the most primitive invertebrates to have a brain. The evolutionary history of flatworms is uncertain, but they share some basic characteristics with rotifers, nematodes, and a few other invertebrate phyla. Cestodes (tapeworms), planarians, and trematodes (flukes) are flatworms.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.