insulator

A material that insulates, especially a nonconductor of sound, heat, or electricity.

A device that insulates.

One who or that which insulates; specifically, a substance or body that interrupts the communication of electricity or heat to surrounding objects; a non-conductor; anything through which an electric current will not pass.

One who, or that which, insulates.

A substance or object that insulates; a nonconductor.

A substance that does not transmit heat (thermal insulator), sound (acoustic insulator) or electricity (electrical insulator).

A non–conductive structure, coating or device that does not transmit sound, heat or electricity (see image)

a material such as glass or porcelain with negligible electrical or thermal conductivity