Why this word is great
IDOLUM — [Noun] An insubstantial image, such as a phantom or a misleading mental conception. From the Latin īdōlum ("apparition, mental image, idol"), itself from the Greek eidōlon ("image, phantom"). Unlike an "idol," a tangible object of veneration, or a "concept," a scaffold for abstract thought, an idolum is the spectral residue of the mind’s own projection. It is the face conjured from a stranger's retreating back, the flawless argument that dissolves upon waking, or the silhouette in a dim hallway that resolves into a coat on a chair. We are haunted not by ghosts, but by the sharper, more persuasive phantoms our own minds project.