"Will o' the wisp" is a term that refers to a ghostly light that seems to appear and disappear unpredictably in the darkness. This phenomenon is also known as ignis fatuus, jack-o'-lantern, and fairy light. Other synonyms for this term include corpse candle, spook light, and flicker flame. In legends and folklore, these lights are believed to be the spirits of the dead or mischievous fairies who lead people astray. No matter what you call it, the will o' the wisp continues to fascinate and intrigue people, adding an element of mystery to the darkness of the night.