/ig"nis fach"ooh euhs/ , pl. ignes fatui /ig"neez fach"ooh uy'/ .
1. Also called friar's lantern, will-o'-the-wisp . a flitting phosphorescent light seen at night, chiefly over marshy ground, and believed to be due to spontaneous combustion of gas from decomposed organic matter.
2. something deluding or misleading.
[ 1555-65; ]