tapeworm

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various long segmented parasitic flatworms of the class Cestoda that lack a digestive system and have hooks or suckers for attaching to the intestines of vertebrates, including humans.

from The Century Dictionary.

• noun An entozoic parasitic worm, of flattened or tape-like form and indeterminate length, consisting of many separable joints, found in the adult state in the alimentary canal of most vertebrated animals.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) Any one of numerous species of cestode worms belonging to Tænia and many allied genera. The body is long, flat, and composed of numerous segments or proglottids varying in shape, those toward the end of the body being much larger and longer than the anterior ones, and containing the fully developed sexual organs. The head is small, destitute of a mouth, but furnished with two or more suckers (which vary greatly in shape in different genera), and sometimes, also, with hooks for adhesion to the walls of the intestines of the animals in which they are parasitic. The larvæ (see cysticercus) live in the flesh of various creatures, and when swallowed by another animal of the right species develop into the mature tapeworm in its intestine. See Illustration in Appendix.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any parasitical worm of the class Cestoda, which infest the intestines of both animals and humans.
• noun A broad fish tapeworm, Diphyllobothrium latum.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun ribbonlike flatworms that are parasitic in the intestines of humans and other vertebrates