noun
will-o'-the-wisp; phosphorescent light
Refers to a mysterious, flickering light seen at night over marshes or graveyards, traditionally attributed to supernatural causes but scientifically explained as spontaneous combustion of marsh gases. The term is somewhat literary or folkloric.
夜の墓地で燐火を見たという話を聞いた。
I heard a story about seeing a will-o'-the-wisp in the graveyard at night.
燐火は科学的には自然発火現象とされる。
Will-o'-the-wisps are scientifically considered a spontaneous combustion phenomenon.