insulator

noun

1. Electricity.
   1. a material of such low conductivity that the flow of current through it is negligible.
   2. insulating material, often glass or porcelain, in a unit form designed so as to support a charged conductor and electrically isolate it.
2. a person or thing that insulates.

noun

1. any material or device that insulates, esp a material with a very low electrical conductivity or thermal conductivity or something made of such a material

n.

1801, agent noun in Latin form from insulate.

1. A material or an object that does not easily allow heat, electricity, light, or sound to pass through it. Air, cloth and rubber are good electrical insulators; feathers and wool make good thermal insulators. Compare conductor.

A material that does not easily transmit energy, such as electric current (see also current) or heat. Materials such as wood, plastic, and ceramics are insulators. Fiberglass is an example of a heat insulator. (Compare conductor.)