Definition of "phantom"

A ghost or apparition.  examples

Something apparently seen, heard, or sensed, but having no physical reality; an image that appears only in the mind; an illusion or delusion.  examples

(bridge) A placeholder for a pair of players when there are an odd number of pairs playing.  examples

(medical imaging) A test object. A test phantom is an object that reproduces the characteristics of human tissue.  examples

Illusive.  quotations  examples

Fictitious or nonexistent.  examples