c. 1300, fantum, famtome, "illusion, unreality; an illusion," senses now obsolete, 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 "a 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. (Coleridge used phantomatic for "phantom-like, unreal"). Phantom limb "sensation of the presence of an amputated arm or leg" is attested by 1871.
mid-13c., fantesme, "that which has only seeming reality, permanence, or value;" c. 1300 as "an illusory experience or object; an apparition;" from Old French fantosme "a dream, illusion, fantasy; apparition, ghost, phantom" (12c.), and directly from Latin phantasma "an apparition, specter," in Late Latin also "appearance, image," 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; come to light, be seen, appear; explain, expound, inform against; appear to be so," from PIE root *bha- (1) "to shine." Spelling conformed to Latin from 16c. (see ph). A spelling variant of phantom, "differentiated, but so that the differences are elusive" [Fowler].
"fantastic series or medley of illusive or terrifying figures or images," 1802, the name of a magic lantern exhibition brought to London in 1802 by Parisian showman Paul de Philipstal. The name is an alteration of French phantasmagorie, which is said to have been coined 1801 by French dramatist Louis-Sébastien Mercier as though to mean "crowd of phantoms," from Greek phantasma "image, phantom, apparition" (from PIE root *bha- (1) "to shine").
The second element appears to be a French form of Greek agora "assembly. "But the inventor of the word prob. only wanted a mouth-filling and startling term, and may have fixed on -agoria without any reference to the Greek lexicon" [OED]. The transferred meaning "shifting scene of many elements" is attested from 1822. Related: Phantasmagorical.
In Philipstal's 'phantasmagoria' the figures were made rapidly to increase and decrease in size, to advance and retreat, dissolve, vanish, and pass into each other, in a manner then considered marvellous. [OED]
Old English gast "breath; good or bad spirit, angel, demon; person, man, human being," in Biblical use "soul, spirit, life," from Proto-West Germanic *gaistaz (source also of Old Saxon gest, Old Frisian jest, Middle Dutch gheest, Dutch geest, German Geist "spirit, ghost"). This is conjectured to be from a PIE root *gheis-, used in forming words involving the notions of excitement, amazement, or fear (source also of Sanskrit hedah "wrath;" Avestan zaesha- "horrible, frightful;" Gothic usgaisjan, Old English gæstan "to frighten").
Ghost is the English representative of the usual West Germanic word for "supernatural being." In Christian writing in Old English it is used to render Latin spiritus (see spirit (n.)), a sense preserved in Holy Ghost. Sense of "disembodied spirit of a dead person," especially imagined as wandering among the living or haunting them, is attested from late 14c. and returns the word toward its likely prehistoric sense.
Most Indo-European words for "soul, spirit" also double with reference to supernatural spirits. Many have a base sense of "appearance" (such as Greek phantasma; French spectre; Polish widmo, from Old Church Slavonic videti "to see;" Old English scin, Old High German giskin, originally "appearance, apparition," related to Old English scinan, Old High German skinan "to shine"). Other concepts are in French revenant, literally "returning" (from the other world), Old Norse aptr-ganga, literally "back-comer." Breton bugelnoz is literally "night-child." Latin manes probably is a euphemism.
The gh- spelling appeared early 15c. in Caxton, influenced by Flemish and Middle Dutch gheest, but was rare in English before mid-16c. Sense of "slight suggestion, mere shadow or semblance" (in ghost image, ghost of a chance, etc.) is first recorded 1610s; sense of "one who secretly does work for another" is from 1884. Ghost town is from 1908. Ghost story is by 1811. Ghost-word "apparent word or false form in a manuscript due to a blunder" is from 1886 (Skeat). Ghost in the machine was British philosopher Gilbert Ryle's term (1949) for "the mind viewed as separate from the body." The American Indian ghost dance is from 1890. To give up the ghost "die" was in Old English.