insulator

American  

[in-suh-ley-ter, ins-yuh-] / ˈɪn səˌleɪ tər, ˈɪns yə- /

noun

1. Electricity.

   1. a material of such low conductivity that the flow of current through it is negligible.

   2. insulating material, often glass or porcelain, in a unit form designed so as to support a charged conductor and electrically isolate it.

2. a person or thing that insulates.

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insulator British  

/ ˈɪnsjʊˌleɪtə /

noun

1. any material or device that insulates, esp a material with a very low electrical conductivity or thermal conductivity or something made of such a material

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insulator Scientific  

/ ĭn′sə-lā′tər /

1. A material or an object that does not easily allow heat, electricity, light, or sound to pass through it. Air, cloth and rubber are good electrical insulators; feathers and wool make good thermal insulators.

2. Compare conductor

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insulator Cultural  

1. A material that does not easily transmit energy, such as electric current (see also current) or heat. Materials such as wood, plastic, and ceramics are insulators. Fiberglass is an example of a heat insulator. (Compare conductor.)

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Other Word Forms

• noninsulator noun

Etymology

Origin of insulator

First recorded in 1795–1805; insulate + -or ²

Example Sentences

A typical double-hung window—even a double-glazed one—is so leaky, and such a poor insulator, that if your home were a bucket, your windows are effectively holes in it.

From The Wall Street Journal • Nov. 21, 2025

"It's the whole compound that behaves like a metal even though it's an insulator."

From Science Daily • Nov. 9, 2025

Semiconductors, as the name suggests, can partially conduct electricity - alternating between doing so and acting as an insulator.

From BBC • Aug. 7, 2025

It is a better thermal insulator and was previously sold to stabilise failing roofs.

From BBC • Nov. 17, 2024

“Do nothing more than look for the new boxes. When Oakley Street’s put a new insulator in place, I’ll let you know.”

From "The Book of Dust: La Belle Sauvage" by Philip Pullman