Any of the liver flukes (parasitic trematode flatworms) of the genus Fasciola (family Fasciolidae), the members of which feed and reproduce in the liver and biliary tract of sheep, cattle, and other mammals (including humans); especially the fluke F. hepatica, which is a major cause of disease in sheep. Also (in form Fasciola): the genus itself (frequently as a modifier).

In full "fasciola cinerea". Originally: †an area of grey matter associated with the termination of the cochlear nerve (probably the dorsal and ventral cochlear nuclei) (obsolete). In later use: a band of grey matter extending between the posterior part of the hippocampus and the corpus callosum on each side; a fasciolar gyrus.