A dielectric's a nonconducting substance, for example an insulator. The term was coined by William Whewell in response to a request from Michael Faraday. Although "dielectric" and "insulator" are generally considered synonymous, the term "dielectric"'s more often used to describe the insulating material between the metallic plates of a capacitor, while "insulator"'s more often used when the material's being used to prevent a current flow across it. Dielectrics's the study of dielectric material… (More on Dielectric)