'Nonconductor' definitions:

Definition of 'nonconductor'

noun

A material such as glass or porcelain with negligible electrical or thermal conductivity [syn: insulator, dielectric, nonconductor] [ant: conductor]

From: GCIDE

Nonconductor \Non`con*duct"or\, n. (Physics) 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]