Phantom

phantom
That which has only an apparent existence; an apparition; a specter; a phantasm; a sprite; an airy spirit; an ideal image. Strange phantoms rising as the mists arise. (pope) She was a phantom of delight. (Wordsworth) Phantom ship. See flying dutchman, under Flying.
(Science: medicine) Phantom tumour, a swelling, especially of the abdomen, due to muscular spasm, accumulation of flatus, etc, simulating an actual tumour in appearance, but disappearing upon the administration of an anaesthetic.
Origin: OE. Fantome, fantosme, fantesme, OF. Fantome, fr. L. Phantasma, Gr, fr. To show. See Fancy, and cf. Phaeton, Phantasm, Phase.