A phantom is something that appears to exist but isn't really there, or isn't what it seems to be. The word originally described a ghost or spirit, something you might glimpse in the shadows but can't actually touch or prove exists.

In everyday use, phantom often describes sensations or experiences that feel real but have no physical cause. Doctors talk about phantom pain, when someone who has lost a limb still feels pain where that limb used to be. The nerves and brain remember what should be there, creating a very real sensation of something that no longer exists. Athletes sometimes experience phantom sounds, hearing a whistle blow during practice when no whistle actually sounded.

The word also describes things that are mysterious or hard to pin down. A phantom caller might hang up whenever you answer the phone. A phantom of the opera haunts a theater, appearing and disappearing mysteriously. In baseball, a phantom tag happens when a fielder pretends to touch a base or runner but doesn't quite make contact.

When you hear phantom, think of something that seems present but proves elusive or unreal when you try to examine it closely: more shadow than substance, more impression than fact.