insulator
n. countable B2 Upper Intermediate US //ˈɪnsəˌɫeɪtɝ// UK //ˈɪnsuːlˌeɪtɐ// in·su·la·tor
n. a material that stops heat, electricity, or sound from moving through it. You use it to keep things warm or to protect you from electric shocks.
n. a material that resists the flow of heat, electricity, or sound. Often used in the context of thermal or electrical safety.
Wool is a good insulator for keeping you warm.
The electrician wore rubber gloves because rubber is an excellent insulator that prevents shocks.
In high-voltage power lines, ceramic insulators are used to prevent the current from leaking into the surrounding air or the metal towers that support the cables.
From insulate + -or.