insulator
noun
in·su·la·tor ˈin(t)-sə-ˌlā-tər 
: one that insulates: such as
a
: a material that is a poor conductor (as of electricity or heat) compare semiconductor
b
: a device made of an electrical insulating material and used for separating or supporting conductors
Example Sentences
Metal is not a good insulator.
Recent Examples on the Web Penguins also have genes for white fat, a crucial insulator and energy source not found in other birds that aids in migrating and surviving cold temperatures, per the ABC. 
Will Sullivan, Smithsonian Magazine, 20 July 2022 The molecules of the two substances realign to form what's known as an intermetallic—a hard and brittle material that acts as an insulator. Wired, 15 July 2022 The coop is using software from Texas A&M that monitors its high-risk distribution lines and can pinpoint specific issues, such as a cracked insulator that could bleed electricity onto a pole and start a fire. oregonlive, 22 June 2022 This aerobic insulator is the mullet of puffy jackets, combining baffles of ultralight synthetic insulation up front and laser-cut perforated ventilation in the back. Frederick Reimers, Outside Online, 29 Mar. 2022 Aside from being accessible at a range of price points, wall-to-wall carpeting is also beloved for being a natural insulator. Natalie Stoclet, House Beautiful, 24 May 2022 Each layer sandwiches a vacuum that acts as an insulator. Manasee Wagh, Popular Mechanics, 18 Apr. 2022 The Novus Hoody is the indispensable layer: a fantastic wet-weather insulator when paired with a hard shell, and a stand-alone soft shell for the skin track. Frederick Reimers, Outside Online, 29 Mar. 2022 This 12-ounce can insulator is perfect for keeping beverages cold during warm-weather adventures, from soft drinks to something a bit more adult. Breanna Wilson, Forbes, 18 Mar. 2022 See More
Will Sullivan, Smithsonian Magazine, 20 July 2022 The molecules of the two substances realign to form what's known as an intermetallic—a hard and brittle material that acts as an insulator. Wired, 15 July 2022 The coop is using software from Texas A&M that monitors its high-risk distribution lines and can pinpoint specific issues, such as a cracked insulator that could bleed electricity onto a pole and start a fire. oregonlive, 22 June 2022 This aerobic insulator is the mullet of puffy jackets, combining baffles of ultralight synthetic insulation up front and laser-cut perforated ventilation in the back. Frederick Reimers, Outside Online, 29 Mar. 2022 Aside from being accessible at a range of price points, wall-to-wall carpeting is also beloved for being a natural insulator. Natalie Stoclet, House Beautiful, 24 May 2022 Each layer sandwiches a vacuum that acts as an insulator. Manasee Wagh, Popular Mechanics, 18 Apr. 2022 The Novus Hoody is the indispensable layer: a fantastic wet-weather insulator when paired with a hard shell, and a stand-alone soft shell for the skin track. Frederick Reimers, Outside Online, 29 Mar. 2022 This 12-ounce can insulator is perfect for keeping beverages cold during warm-weather adventures, from soft drinks to something a bit more adult. Breanna Wilson, Forbes, 18 Mar. 2022 See More Word History
First Known Use
1801, in the meaning defined above
Kids Definition
insulator
noun
in·su·la·tor ˈin-sə-ˌlā-tər
: a material (as rubber or glass) that is a poor conductor of electricity, heat, or sound
Medical Definition
insulator
noun
in·su·la·tor ˈin(t)-sə-ˌlāt-ər
: a material that is used to provide insulation
also : a device made of such material