I am going to use this word in some future post and I just thought you might like to know what it meant beforehand.

Friar's lantern (FRY-uhrz LAN-tuhrn) noun

A phosphorescent light seen over marshy ground at night, caused by spontaneous combustion of gases emitted by decomposing organic matter. A synonym if foxfire (not Firefox), especially for luminescence by fungi.

[The first use of the term is in John Milton's 1632 poem L'Allegro: "She was pinched and pulled, she said/And he, by Friar's lantern led."]