Synonyms

Styrofoam

American

[stahy-ruh-fohm] / ˈstaɪ rəˌfoʊm /

Trademark.

a brand of expanded plastic made from polystyrene.

Styrofoam British

/ ˈstaɪrəˌfəʊm /

noun

(sometimes not capital) a light, expanded polystyrene plastic

"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

Etymology

Origin of Styrofoam

C20: from _polystyrene + _foam

Compare meaning

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

polystyrene vs. Styrofoam

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The cause of the blaze remains unclear but officials said on Friday that Styrofoam placed on the outside of the windows facilitated its rapid spread.

From BBC • Nov. 28, 2025

She then reached for a Styrofoam mannequin’s head that was on a shelf in the closet.

From Slate • Nov. 15, 2025

On blustery afternoons, my street’s geography sends every scrap of airborne litter to my curb: candy wrappers, Styrofoam peanuts and Trader Joe’s receipts that reveal too much about the neighbors’ taquitos intake.

From The Wall Street Journal • Oct. 8, 2025

I helped implement a plastic bag and Styrofoam ban, designed a food waste composting system at my high school and local gardens and created eco-friendly living PSAs.

From Los Angeles Times • Sep. 15, 2024

There was a Styrofoam coffee cup propped up next to the gearshift and a cigar smoldering in a metal ashtray sticking out of the dashboard.

From "The Honest Truth" by Dan Gemeinhart

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023