• synonyms


[in-suh-ley-ter, ins-yuh-]
  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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Origin of insulator

First recorded in 1795–1805; insulate + -or2
Related formsnon·in·su·la·tor, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for insulator

Historical Examples

  • Each one that will not make it ring is a poor conductor or an insulator.

    Common Science

    Carleton W. Washburne

  • It must therefore be considered rather as a partial conductor than as an insulator.

    On Laboratory Arts

    Richard Threlfall

  • The action of its particles differs from those of an insulator only in degree.

  • The wood is used for posts, cross-ties, wagon hubs, and insulator pins.

    Studies of Trees

    Jacob Joshua Levison

  • Speaking generally, the conductors are separated by some insulator.

British Dictionary definitions for insulator


  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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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for insulator


1801, agent noun in Latin form from insulate.

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Online Etymology Dictionary, © 2010 Douglas Harper

insulator in Science


  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. Compare conductor.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

insulator in Culture


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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The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.