A nonconducting substance used as insulation.
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in·su·la·tor 'in(t)-sə-.lāt-ər n a material that is used to provide insulation also a device made of such material
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in·su·la·tor (inґsə-la″tər) any substance or appliance of such nonconducting properties that it can be used to secure insulation.Medical dictionary. 2011.