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[pol-ee-stahy-reen, -steer-een] /ˌpɒl iˈstaɪ rin, -ˈstɪər in/
noun, Chemistry
a clear plastic or stiff foam, a polymer of styrene, used chiefly as an insulator in refrigerators and air conditioners.
Origin of polystyrene
1925-30; poly- + styrene Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for polystyrene
  • The walls were lined with aged polystyrene foam blocks for insulation.
  • They started with a collection of spherical polystyrene pellets.
  • They're space efficient too: a one-inch-thick ash panel equals today's four-inch-thick polystyrene panels.
  • Anglers often use a piece of a milk jug, polystyrene foam, chopped-up swimming noodles and other plastic chunks.
  • The two firms have already started combining some of their businesses, such as polystyrene.
  • However, this slab is punctured by a hexagonal array of holes that correspond to the position of the polystyrene beads.
  • F acing environmentalists' ire, fast-food franchises switched from polystyrene burger boxes to cardboard several years back.
  • The past decade has brought a new approach: building floating structures on platforms of polystyrene and concrete.
  • The interior is also now decked with modern kitsch: bits of tinsel, polystyrene, and a halo of fairy lights.
  • polystyrene is an odorless, tasteless, rigid thermoplastic.
British Dictionary definitions for polystyrene


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
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
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Word Origin and History for polystyrene

1922, so called because it is a polymer of styrene.

Online Etymology Dictionary, © 2010 Douglas Harper
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polystyrene in Science
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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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