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ignis fatuus - 5 dictionary results

ig⋅nis fat⋅u⋅us

[ig-nis fach-oo-uhs]
–noun, plural ig⋅nes fat⋅u⋅i [ig-neez fach-oo-ahy] .
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.

Origin:
1555–65; < ML: lit., foolish fire
ig·nis fat·u·us   (ĭg'nĭs fāch'ōō-əs)   
n.   pl. ig·nes fat·u·i (ĭg'nēz fāch'ōō-ī')
  1. A phosphorescent light that hovers or flits over swampy ground at night, possibly caused by spontaneous combustion of gases emitted by rotting organic matter. Also called friar's lantern, jack-o'-lantern, will-o'-the-wisp, wisp.
  2. Something that misleads or deludes; an illusion.

[Medieval Latin : Latin ignis, fire + Latin fatuus, foolish.]

Ignis fatuus

Ig"nis fat"u*us\; pl. Ignes fatui. [L. ignis fire + fatuus foolish. So called in allusion to its tendency to mislead travelers.]

1. A phosphorescent light that appears, in the night, over marshy ground, supposed to be occasioned by the decomposition of animal or vegetable substances, or by some inflammable gas; -- popularly called also Will-with-the-wisp, or Will-o'-the-wisp, and Jack-with-a-lantern, or Jack-o'-lantern.

2. Fig.: A misleading influence; a decoy.

Scared and guided by the ignis fatuus of popular superstition. --Jer. Taylor.

ignis fatuus 
"will o' the wisp, jack-a-lantern," 1563, from M.L., lit. "foolish fire." It seems once to have been more common than presently.

ignis fatuus

in meteorology, a mysterious light seen at night flickering over marshes; when approached, it advances, always out of reach. The phenomenon is also known as will-o'-the-wisp and ignis fatuus (Latin: "foolish fire"). In popular legend it is considered ominous and is often purported to be the soul of one who has been rejected by hell carrying its own hell coal on its wanderings. The phenomenon is generally believed to be due to the spontaneous ignition of marsh gas, which consists mostly of methane and which is produced by the decomposition of dead plant matter

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