- noun a measure of how well a non-conducting material retains electrical energy when placed in an electric field
- The property of a material which determines the electrostatic energy that can be stored per unit volume for a unit potential gradient. This is equivalent to the ratio of the capacitance of a capacitor using the material in question as a dielectric, to the capacitance of a capacitor using a vacuum as a dielectric. Its symbol is ∈. Also called dielectric constant, relative permittivity, inductivity, and specific inductive capacity.