Polystyrene is a very light plastic substance used to make containers or to keep things warm, cool, or protected from damage.
...polystyrene cups.
polystyrene in British English
(ˌpɒlɪˈstaɪriːn)
noun
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
polystyrene in American English
(ˌpɑlɪˈstaɪˌrin)
noun
a tough, clear, colorless plastic material, a polymer of styrene, used to make chemical apparatus, containers, etc.
Examples of 'polystyrene' in a sentence
polystyrene
The worst thing was this polystyrene sheeting we'd glued down to keep the damp and the cold out.
Dexter Petley WHITE LIES (2002)
The other two desks were unmanned, but filled with file folders, papers, and empty polystyrene coffee cups.