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ignis fatuus

[ ig-nis -fach-oo-uhs ]
/ ˈɪg nɪs ˈfætʃ u əs /
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noun, plural ig·nes fat·u·i [ig-neez -fach-oo-ahy]. /ˈɪg niz ˈfætʃ uˌaɪ/.
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.
something deluding or misleading.
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Origin of ignis fatuus

1555–65; <Medieval Latin: literally, foolish fire
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

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British Dictionary definitions for ignis fatuus

ignis fatuus
/ (ˈɪɡnɪs ˈfætjʊəs) /

noun plural ignes fatui (ˈɪɡniːz ˈfætjʊˌaɪ)
another name for will-o'-the-wisp

Word Origin for ignis fatuus

C16: from Medieval Latin, literally: foolish fire
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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