Definition of brainworm in English:



  • 1A worm imagined as infesting the brain. Chiefly figurative.

  • 2Zoology and Veterinary Medicine. Any of various parasitic worms that infect the brains of mammals or other vertebrates; especially any nematode of the genera Elaphostrongylus and Parelaphostrongylus (family Protostrongylidae), which parasitize the central nervous system and certain other tissues of deer. Also (without article): worms of this kind.

  • 3Zoology. A liver fluke, Dicrocoelium dendriticum (family Dicrocoelidae), which parasitizes many species of mammal (and occasionally humans), and has a cercarial stage which enters the brain of an intermediate host, the ant, resulting in behavioural changes conducive to transmission to mammals.


Early 17th century; earliest use found in Richard Brathwait (?1588–1673), poet and writer. From brain + worm.