Ignis fatuus, a faintly luminous flame which hovers over marshy places is known as a Jack O' Lantern or what?
Jack-o'-lantern form a lid, the inside flesh is scooped out, and an image — usually a scary or funny face – is carved out of the rind to expose the hollow interior. To create the lantern effect, a light source, traditionally a flame such as a candle or tea light, is placed within before the lid is closed. However, artificial jack-'o-lanterns with electric lights are also marketed. It is common to see jack-o'-lanterns on doorsteps and otherwise used as decorations prior to and on Halloween. The term "jack-o'-lantern" was originally used to describe the visual phenomenon "ignis fatuus" (lit., "foolish fire")
Jack-o'-lantern the legend of "Jack-o'-the-Lantern". In 1837, the "Limerick Chronicle" refers to a local pub holding a carved gourd competition and presenting a prize to "the best crown of Jack McLantern". The term "McLantern" also appears in an 1841 publication of the same paper. There is also evidence that turnips were used to carve what was called a "Hoberdy's Lantern" in Worcestershire, England, at the end of the 18th century. The folklorist Jabez Allies recalls: Adaptations of Washington Irving's short story "The Legend of Sleepy Hollow" (1820) often show the Headless Horseman with a pumpkin or jack-o'-lantern in place of his