material that is used to stop the passage of electricity, heat, or sound from one conductor to another.

An insulating material used in bulk to wrap electrical cables or other equipment is called insulation. The term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers.

separate with a material that prevents or reduces the passage, transfer, or leakage of heat, electricity, or sound: to insulate an electric wire with a rubber sheath; to insulate a coat with down