The Collaborative International Dictionary
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.]
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.
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Fig.: A misleading influence; a decoy.
Scared and guided by the ignis fatuus of popular superstition.
--Jer. Taylor.
Will-o'-the-wisp \Will"-o'-the-wisp`\, n. See Ignis fatuus.
Douglas Harper's Etymology Dictionary
1660s, earlier Will with the wisp (c.1600), from the masc. proper name Will + wisp "bundle of hay or straw used as a torch." Compare Jack o'lantern.
Wiktionary
n. (alternative spelling of will o' the wisp English)
WordNet
n. a pale light sometimes seen at night over marshy ground [syn: friar's lantern, ignis fatuus, jack-o'-lantern]
an illusion that misleads [syn: ignis fatuus]
Wikipedia
A will-o'-the-wisp , will-o'-wisp , or ignis fatuus (; Medieval Latin: "foolish fire") is an atmospheric ghost light seen by travellers at night, especially over bogs, swamps or marshes. It resembles a flickering lamp and is said to recede if approached, drawing travellers from the safe paths. The phenomenon is known by a variety of names, including jack-o'-lantern, friar's lantern, hinkypunk, and hobby lantern in English folk belief, well attested in English folklore and in much of European folklore.
Will-o'-the-wisp is the light phenomenon traditionally ascribed to ghosts.
Will-o'-the-wisp may refer to:
Usage examples of "will-o'-the-wisp".
But always in that nightmare the Saint's fantastic optimism led him on, dancing ahead like a will-o'-the-wisp, trailing him dizzily behind into hell-for-leather audacities which Roger, in the more leisured days that followed, would remember in a cold sweat.
One gathered from it that that elusive and distressingly picturesque outlaw, the Saint, had set the Law by the ears again with a new climax of audacities: his name and nom de guerre waltzed through the bald paragraphs of the narrative like a debonair will-o'-the-wisp, carrying with it a breath of buccaneering glamour, a magnificently medieval lawlessness, that shone with a strange luminance through the dull chronicles of an age of dreary news.
Your scientific methods instead of leading you onward towards the Central Sun of Spiritual enlightenment has so beclouded your vision that your race today--that is, the so-called enlightened and learned portions of your population--have been deflected from the main path, and they will soon find themselves pursuing an illusionary will-o'-the-wisp.
And the conceit pleased him, and he felt sympathy for the strange, will-o'-the-wisp editor who had so befriended Hawaii and the missionaries, until he suddenly looked at the name again: James Jackson Jarves!
And that's something quite unusual even in Fantastica, because ordinarily will-o'-the-wisps make others lose their way.
The interior door was a rectangle of light fainter than a will-o'-the-wisp.
One of the will-o'-the-wisp servants guided Eric through the labyrinth of interconnecting castle rooms all filled with revelers, finally arriving at the castle's equivalent of the RenFaire's Main Stage.
The wizards of Tunland's Ravagers stood behind the Sable Daggers, amusing themselves with will-o'-the-wisps and clouds of dancing smoke.