polystyrene

American  

[pol-ee-stahy-reen, -steer-een] / ˌpɒl iˈstaɪ rin, -ˈstɪər in /

noun

Chemistry.

1. a clear plastic or stiff foam, a polymer of styrene, used chiefly as an insulator in refrigerators and air conditioners.

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polystyrene British  

/ ˌpɒlɪˈstaɪriːn /

noun

1. a synthetic thermoplastic material obtained by polymerizing styrene; used as a white rigid foam ( expanded polystyrene ) for insulating and packing and as a glasslike material in light fittings and water tanks

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polystyrene Scientific  

/ pŏl′ē-stī′rēn /

1. A brittle synthetic polymer composed of repeated styrene units. Polystyrene is transparent and rigid because the benzene rings in each styrene unit prevent the polystyrene chains from arranging themselves into a tight crystalline structure. Polystyrene has a wide variety of uses, especially as a solid foam for insulation and packaging.

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Etymology

Origin of polystyrene

First recorded in 1925–30; poly- + styrene

Compare meaning

How does polystyrene compare to similar and commonly confused words? Explore the most common comparisons:

• polystyrene vs. Styrofoam

Example Sentences

See Examples For:

polystyrene

She also raised the alarm about what she thought were bombs, but the prosecution explained that several plastic bottles filled with polystyrene were found, and no explosives.

From BBC ● May 18, 2026

Wilson believes that Snow Secure—the high-tech insulated polystyrene blanket that unfolds like an accordion, then drapes over a pile of snow—is just the invention.

From Slate ● Apr. 11, 2026

To recreate the animal, researchers constructed the torso using polystyrene foam and a wooden frame, then added cotton, bubble paper, and fabric to mimic soft tissues.

From Science Daily ● Mar. 19, 2026

Airport authorities and police seized six pieces of rhinoceros horn and around 12 kilograms of unidentified meat used to conceal them inside a polystyrene icebox.

From Barron's ● Feb. 10, 2026

Dry little pellets of snow, like tiny spheres of polystyrene, chased around in swirls.

From "A Walk in the Woods" by Bill Bryson