The Collaborative International Dictionary of English v.0.48:
Phantom \Phan"tom\, n. [OE. fantome, fantosme, fantesme, OF.
fant[^o]me, fr. L. phantasma, Gr. fa`ntasma, fr. fai`nein to
show. See Fancy, and cf. Pha["e]ton, Phantasm,
That which has only an apparent existence; an apparition; a
specter; a phantasm; a sprite; an airy spirit; an ideal
Strange phantoms rising as the mists arise. --Pope.
She was a phantom of delight. --Wordsworth.
Phantom ship. See Flying Dutchman, under Flying.
Phantom tumor (Med.), a swelling, especially of the
abdomen, due to muscular spasm, accumulation of flatus,
etc., simulating an actual tumor in appearance, but
disappearing upon the administration of an an[ae]sthetic.