Meaning

noun a ghostly appearing figure

noun something existing in perception only

adjective something apparently sensed but having no physical reality

originInherited from Middle English fantome, fanteme, from Old French fantosme, fantasme, from Latin phantasma (“an apparition, specter; (in Late Latin also) appearance, image”), from Ancient Greek φάντασμα (phántasma, “phantasm, an appearance, image, apparition, specter”), from φαντάζω (phantázō, “to make visible”). Doublet of phantasm.

Etymology from Wiktionary, CC BY-SA 3.0