Final answer:
A ghost task is also known as a phantom task, often used as a placeholder in project management.
Step-by-step explanation:
Another name for a ghost task is a phantom task. In project management and scheduling, a ghost or phantom task refers to a placeholder task used to represent an external dependency or another piece of work that does not have a direct output or product. They are often used in project schedules to block out time or to account for the impact of external factors that are not within the direct control of the project team.