ghost

noun

• an apparition of a dead person which is believed to appear or become manifest to the living, typically as a nebulous image:the building is haunted by the ghost of a monk [as modifier]:a ghost ship
• a slight trace or vestige of something:she gave the ghost of a smile
• a faint secondary image produced by a fault in an optical system or on a cathode ray screen, e.g. by faulty television reception or internal reflection in a mirror or camera.

verb

• 1 [with object] act as ghostwriter of (a work):his memoirs were smoothly ghosted by a journalist

• 2 [no object, with adverbial of direction] glide smoothly and effortlessly:they ghosted up the river