Dielectric

adj. of or pertaining to a dielectric substance, of or pertaining to a material that does not conduct electricity

n. insulator, material that does not conduct electricity

A dielectric is a physical model commonly used to describe how an electric field behaves inside a material. It is characterised by how an electric field interacts with an atom. It is possible to approach dielectrics from either a classical interpretation or a quantum one. However, the classical is much more intuitive.
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Noun
1. a material such as glass or porcelain with negligible electrical or thermal conductivity
(synonym) insulator, nonconductor
(hypernym) material, stuff
(hyponym) bushing

(n.)
Any substance or medium that transmits the electric force by a process different from conduction, as in the phenomena of induction; a nonconductor. separating a body electrified by induction, from the electrifying body.
  

1. A substance in which an electric field may be maintained with zero or near-zero power dissipation, i.e. , the electrical conductivity is zero or near zero. Note 1: A dielectric material is an electrical insulator. Note 2: In a dielectric, electrons are bound to atoms and molecules, hence there are few free electrons. 2. Pertaining to a substance that has a zero or near zero electrical conductivity.