will-o'-the-wisp Meaning, Definition & Usage

  1. noun a pale light sometimes seen at night over marshy ground
    friar's lantern; ignis fatuus; jack-o'-lantern.
  2. noun an illusion that misleads
    ignis fatuus.

WordNet

Will"-o'-the-wisp` noun
Definitions
  1. See Ignis fatuus.

Webster 1913