from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. 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.
  • n. Something that misleads or deludes; an illusion.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A will o' the wisp.
  • n. A delusion, a false hope.

from the GNU version of the Collaborative International Dictionary of English

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

from The Century Dictionary and Cyclopedia

  • A meteoric light that sometimes appears in summer and autumn nights, and flits in the air a little above the surface of the earth, chiefly in marshy places, near stagnant waters, or in churchyards.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. an illusion that misleads
  • n. a pale light sometimes seen at night over marshy ground


Medieval Latin : Latin ignis, fire + Latin fatuus, foolish.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Modern Latin, from ignis (meaning "fire") + fatuus (meaning "foolish"). Literally "foolish fire". (Wiktionary)


  • Let not the magic arts of that worthless Sanford lead you, like an ignis fatuus from the path of rectitude and virtue!

    The Coquette, or, The History of Eliza Wharton: A Novel Founded on Fact

  • And yet they say that the ignis fatuus (as it is called), which sometimes even settles on a wall, has not much heat, perhaps as much as the flame of spirit of wine, which is mild and soft.

    The New Organon

  • When thou rannest up Gadshill in the night to catch my horse, if I did not think thou hadst been an ignis fatuus or a ball of wildfire, there's no purchase in money.

    The First Part of King Henry IV

  • It appears, however, that of all flame that of spirit of wine is the softest, unless perhaps ignis fatuus be softer, and the flames or sparklings arising from the sweat of animals.

    The New Organon


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  • seen in the 1600's under the translation for 'jack with a lantern'

    October 29, 2013

  • also called friar's lantern, jack-o'-lantern, will-o'-the-wisp

    June 14, 2009

  • "With wings wrought from rainbows and eyes from stars, it is but the intangible child of story, song and dream."

    --Agnosticism and Other Essays by Edgar Fawcett

    (q.v.,agnosticism for link)

    July 11, 2008

  • Plural is ignis fatui, as in this marvellous shopping list of faerie beasties:

    "What a happiness this must have been seventy or eighty years ago and upwards, to those chosen few who had the good luck to be born on the eve of this festival of all festivals; when the whole earth was so overrun with ghosts, boggles, bloody-bones, spirits, demons, ignis fatui, brownies, bugbears, black dogs, specters, shellycoats, scarecrows, witches, wizards, barguests, Robin-Goodfellows, hags, night-bats, scrags, breaknecks, fantasms, hobgoblins, hobhoulards, boggy-boes, dobbies, hob-thrusts, fetches, kelpies, warlocks, mock-beggars, mum-pokers, Jemmy-burties, urchins, satyrs, pans, fauns, sirens, tritons, centaurs, calcars, nymphs, imps, incubuses, spoorns, men-in-the-oak, hell-wains, fire-drakes, kit-a-can-sticks, Tom-tumblers, melch-dicks, larrs, kitty-witches, hobby-lanthorns, Dick-a-Tuesdays, Elf-fires, Gyl-burnt-tales, knockers, elves, rawheads, Meg-with-the-wads, old-shocks, ouphs, pad-foots, pixies, pictrees, giants, dwarfs, Tom-pokers, tutgots, snapdragons, sprets, spunks, conjurers, thurses, spurns, tantarrabobs, swaithes, tints, tod-lowries, Jack-in-the-Wads, mormos, changelings, redcaps, yeth-hounds, colt-pixies, Tom-thumbs, black-bugs, boggarts, scar-bugs, shag-foals, hodge-pochers, hob-thrushes, bugs, bull-beggars, bygorns, bolls, caddies, bomen, brags, wraiths, waffs, flay-boggarts, fiends, gallytrots, imps, gytrashes, patches, hob-and-lanthorns, gringes, boguests, bonelesses, Peg-powlers, pucks, fays, kidnappers, gallybeggars, hudskins, nickers, madcaps, trolls, robinets, friars' lanthorns, silkies, cauld-lads, death-hearses, goblins, hob-headlesses, bugaboos, kows, or cowes, nickies, nacks necks, waiths, miffies, buckies, ghouls, sylphs, guests, swarths, freiths, freits, gy-carlins Gyre-carling, pigmies, chittifaces, nixies, Jinny-burnt-tails, dudmen, hell-hounds, dopple-gangers, boggleboes, bogies, redmen, portunes, grants, hobbits, hobgoblins, brown-men, cowies, dunnies, wirrikows, alholdes, mannikins, follets, korreds, lubberkins, cluricauns, kobolds, leprechauns, kors, mares, korreds, puckles korigans, sylvans, succubuses, blackmen, shadows, banshees, lian-hanshees, clabbernappers, Gabriel-hounds, mawkins, doubles, corpse lights or candles, scrats, mahounds, trows, gnomes, sprites, fates, fiends, sibyls, nicknevins, whitewomen, fairies, thrummy-caps, cutties, and nisses, and apparitions of every shape, make, form, fashion, kind and description, that there was not a village in England that had not its own peculiar ghost. Nay, every lone tenement, castle, or mansion-house, which could boast of any antiquity had its bogle, its specter, or its knocker. The churches, churchyards, and crossroads were all haunted. Every green lane had its boulder-stone on which an apparition kept watch at night. Every common had its circle of fairies belonging to it. And there was scarcely a shepherd to be met with who had not seen a spirit!"
    - 'The Denham Tracts' vol. 2, Michael Aislabie Denham, 1895.

    January 4, 2008

  • But, alas! my dear, we see that the wisest people are not to be depended upon when love, like an ignis fatuus, holds up its misleading lights before their eyes.

    Anna Howe to Clarissa Harlowe, Clarissa by Samuel Richardson

    January 4, 2008