1. a lightweight, rigid plastic material made from petroleum, used for insulation, packaging, and disposable food containers
Usage: uncountable; often used in the form of foam or beads

Examples

• The fragile vase was wrapped in polystyrene peanuts for shipping.
• Polystyrene foam is commonly used to insulate buildings and keep food hot or cold.
• Many coffee cups are made from polystyrene because it is inexpensive and durable.
• The takeout container was made of white polystyrene.
• Polystyrene is not biodegradable and takes hundreds of years to decompose in landfills.
• The construction crew used polystyrene boards to insulate the basement walls.