The Collaborative International Dictionary
backworm
Filanders \Fil"an*ders\, n. pl. [F. filandres, fr. L. filum
thread.] (Falconry)
A disease in hawks, characterized by the presence of small
threadlike worms, also of filaments of coagulated blood, from
the rupture of a vein; -- called also backworm.
--Sir T.
Browne.
Wiktionary
backworm
n. A disease of hawks; filanders.