ˈwiləthəˈwisp noun
also will-of-the-wisp -ləfth-
Etymology: Will (nickname for William ) + of + the + wisp
1. : ignis fatuus
2. : a delusive goal
followed the will-o'-the-wisp of universal disarmament — G.F.Eliot
• will-o'-the-wisp·ish -pish adjective