nonconductor(n = noun.substance) dielectric, insulator - a material such as glass or porcelain with negligible electrical or thermal conductivity;
is a kind of material, stuff
has particulars: bushing, mineral wool, rock wool, glass wool

   A substance which does not conduct, that is, convey or transmit, heat, electricity, sound, vibration, or the like, or which transmits them with difficulty; an insulator; as, wool is a nonconductor of heat; glass and dry wood are nonconductors of electricity. [1913 Webster]