The term jack- o’-lantern was first applied not to pumpkins, but people. As far back as 1663, the term meant a man with a lantern, or a night watchman. Just a decade or so later, it began to be used to refer to the mysterious lights sometimes seen at night over bogs, swamps, and marshes.These ghost lights—variously called  jack-o’-lanterns, hinkypunks, hobby lanterns, corpse candles, fairy lights, will-o’-the-wisps, and fool’s fire—are created when gases from decomposing plant matter ignite when they come in contact with electricity or heat or as they oxidize. For centuries before there was this scientific explanation, people told stories to explain the mysterious lights. In Ireland, dating as far back as the 1500s, those stories often revolved around a guy named Jack.