insulator

American  

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

noun

• insulators
  plural

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

Derived Forms

• noninsulator
  noun

Inflected Forms

Nouns

• insulators
  plural

Etymology

Origin of insulator

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

Explanation

Any material that keeps energy such as electricity, heat, or cold from easily transferring through is an insulator. Wood, plastic, rubber, and glass are good insulators. Swiss cheese...not so much. The word insulator comes from the Latin root insulātus, which means "like an island." If your house is built out of good insulators, you might enjoy an island of warmth inside it even during cold winter nights. The opposite of insulator is conductor: a material that easily transmits heat or electricity.

Example Sentences

See Examples For:

insulator insulators

As the density dropped, the flow stopped entirely, and the system became an insulator.

From Science Daily ● Feb. 5, 2026

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

That's because the vest fitted with the cooling system is an insulator and the liquid can end up hotter than the ambient temperature because of the temperature of the cars.

From BBC ● Oct. 2, 2025

Industry experts have told the BBC spray foam is an effective insulator if fitted properly, and urgent action is needed to stop panicked homeowners needlessly turning to "cowboy" removal companies.

From BBC ● Dec. 4, 2024

Our sleeping-bags, coats, and hoods were lined with that same fur, an unsurpassed insulator and very beautiful to see.

From "The Left Hand of Darkness" by Ursula K. Le Guin

The issue had been caused by voids in the cement around the insulators.

From BBC ● Jan. 29, 2026

As part of ENWL's investigation it tested 260 insulators across its network and found 73% contained voids.

From BBC ● Jan. 29, 2026

"Finding insulators that are transparent is really challenging."

From Science Daily ● Dec. 13, 2025

In recent years, however, researchers have discovered the same quantum oscillations in insulators -- materials that should not conduct electricity or heat.

From Science Daily ● Nov. 9, 2025

Cooksey’s new tank compiled everything the lab had learned about how to build a cyclotron into a rugged, gleaming, machined tank with glass insulators and arrangements for air and water cooling.

From "Big Science" by Michael Hiltzik