Dictionary.com
definitions

roundworm

[round-wurm]

noun

any nematode, especially Ascaris lumbricoides, that infests the intestine of humans and other mammals.

Origin of roundworm

First recorded in 1555–65; round1 + worm
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for roundworm

roundworm

noun

any nematode worm, esp Ascaris lumbricoides, a common intestinal parasite of man and pigs
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
Medicine definitions for roundworm

roundworm

[round′wûrm′]

n.

nematode
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.