A phantom subscriber refers to a person who has subscribed to a service or product, but does not actively engage with it or provide any meaningful feedback or interaction. This term is often used in the context of online platforms, where users may sign up for an account but never actually use it, creating a false impression of a larger user base. Phantom subscribers can also refer to individuals who have subscribed to a mailing list or newsletter, but never open or read the emails. Essentially, a phantom subscriber is a ghostly presence that inflates numbers without contributing to the actual success or impact of a product or service.