phantom (n.)
c. 1300, fantum "illusion, unreality," from Old French fantosme (12c.), from Vulgar Latin *fantauma, from Latin phantasma "an apparition," from Greek phantasma "image, phantom, apparition; mere image, unreality," from phantazein "to make visible, display," from stem of phainein "to bring to light, make appear," from PIE root *bha- (1) "to shine." The ph- was restored in English late 16c. (see ph). Meaning "specter, spirit, ghost" is attested from late 14c.; that of "something having the form, but not the substance, of a real thing" is from 1707. As an adjective from early 15c.