ghost bullet

noun6

1. •
   A bullet that is shot by an unseen assailant or one that cannot be seen or heard when it is shot.

   • […] not see them— ghost-bullets flying. — 1966
2. •
   A bullet that cannot be found or that is untraceable through ballistic testing.

   • And the ghost bullet allowed me to introduce new depths of police corruption. — 2012
3. •
   (figurative) Something nonphysical (such as words, actions, or memory) that causes physical or emotional damage.

   • He spoke of radiation as "ghost bullets.” These bullets were deadly if mishandled. — 2013
4. •
   A supernatural bullet that wounds or kills a person, especially one that is shot by a supernatural assailant.

   • People believe that a beast shoots "ghost bullets" when they ford a stream in Sihch'uan at any time except the winter months . — 1968
5. •
   An imaginary bullet.

   • Since nightfall he's bracing himself for the hallucinations he knows are soon to come. Crickets offer their resonant chorus, but they don't drown out the sounds of ghost bullets whistling in the air. — 2011
6. •
   A bullet that can hurt a ghost or undead creature.

   • Hardy wondered what happened to you when you were hit with ghost bullets. Did they only kill ghosts, or could they work on the living, too? — 2010