‖ feu follet|fø fɔlɛ| [Fr., lit. ‘frolicsome fire’.] Ignis fatuus. 1832J. S. Mill Let. 17 July (1910) I. 32 It is possible our light may be nothing but a feu follet.1967Times 7 Sept. 7/5 He [sc. Flaubert] pursued what one must surely regard as the feu follet of ‘pure form’.