Definitions
1.NounA neurotropic nematode parasite (Parelaphostrongylus tenuis).
2.NounAny parasitic, worm-like species that inhabits the brain of another organism, typically altering its behaviour or giving it special abilities.
3.NounA song or melody that keeps playing inside of one's mind. .mw-parser-output .defdate{font-size:smaller}
4.NounA persistent delusion or obsession; a deeply-ingrained or unquestioned idea.