亡霊

1. Origins, structure, and basic meaning

• Structure: 亡霊, read ぼうれい, is a noun referring to the spirit of a dead person.
• Basic usage: 廃屋の窓に亡霊が現れるという噂がある。 reports a rumor that a ghost appears in the window of an abandoned house.

2. Common pitfalls and similar expressions

• A specter of the past
  • 過去の失敗という亡霊 is a metaphor for a past failure that continues to haunt someone. Its referent is a lingering failure, not a dead person.
• Reporting a rumor
  • という噂がある in the first example reports that a rumor exists. It does not state that the speaker personally saw the ghost.