'Insulator' definitions:

Definition of 'insulator'

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

Definition of 'Insulator'

From: GCIDE
  • Insulator \In"su*la`tor\, n.
  • 1. One who, or that which, insulates. [1913 Webster]
  • 2. (Elec. & Thermotics) A substance or object that insulates; a nonconductor; as, polyurethane foam is a popular thermal insulator. [1913 Webster +PJC]