gapeworm

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

• noun A nematode worm (Syngamus trachea) that infects the trachea of certain birds and causes gapes.

from The Century Dictionary.

• noun A nematoid worm, Syngamus trachealis, the cause of gapes in fowls.

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

• noun (Zoöl.) The parasitic worm that causes the gapes in birds. See Illustration in Appendix.

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

• noun A parasitic nematode worm, Syngamus trachea, that infects the tracheas of some birds and causes the disease gapes