The hungry ghosts wandered the streets in search of food.

I saw a group of errand ghosts wandering around the old house.

I saw a group of errand-ghosts wandering around the old abandoned house.

The gauge ghosts are causing interference in the experiment.

The gray ghosts roamed the haunted mansion.

There were many ghosts at the feast.

Pepper's ghosts are optical illusions used in stage magic.

There are many ghosts in machines.

There are many ghosts in the machine.

The old mansion was said to be haunted by long ghosts.