Ghost isn't a every day animal. This means that they don't actually have a name for a group of ghost. So the best term to use is in the question, 'a group of ghosts', or just 'ghosts' on it's own will be fine.
A tort of ghosts.
13 Ghosts
The so called "ghosts" in the Ghost Dance are the spirits of our ancestors.
A person that doesn't believe in ghosts are called skeptics.
They are called poltergeists.
Phasmaphobia.
People who don't believe in ghosts are called skeptics. Skeptics typically demand scientific proof of something before they believe in it. As there is no scientific proof in ghosts, skeptics deem them as being unreal.
It is called 1408.
avp
yes but the like to be called spirits
What u make no sense
Sometimes Ghost's are Spirit's...