This word is borrowed from the Greek “eidōlon,” from “eidos,” which means “form.” The root manifests in both usages of “eidolon” — most obviously as a ghostly form in the “specter or phantom” definition. The eidolon of Hamlet’s father, for example, is a somber presence in the Shakespeare play. According to some accounts, the playwright himself took on the role of the ghost in its original productions. The other use of “eidolon” is akin to the Platonic meaning of “form” (and what the root word meant). To summarize the Greek philosopher Plato, a Form is the ideal essence of something; similarly, an eidolon is the idealized depiction of something.