ignis fatuus

noun

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ig·nis fat·u·us | \ ˈig-nəs-ˈfa-chə-wəs

, -ˈfach-wəs \

plural ignes fatui\ ˈig-ˌnēz-ˈfa-chə-ˌwī

Definition of ignis fatuus

1 : a light that sometimes appears in the night over marshy ground and is often attributable to the combustion of gas from decomposed organic matter

2 : a deceptive goal or hope

Examples of ignis fatuus in a Sentence

Recent Examples on the Web The story also helped explain ignis fatuus, a natural phenomenon that occurs in marshlands and bogs—such as those in Ireland’s countryside—producing flickering lights as gases from decomposing organic matter combust. — National Geographic, "The twisted transatlantic tale of American jack-o’-lanterns," 27 Oct. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ignis fatuus.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.