/ Dictionary / Index S Styrofoam: Meaning and Definition of Find definitions for: Sty•ro•foam Pronunciation: (stī'ru-fōm"), [key] — Trademark. Trademark. a brand of expanded plastic made from polystyrene. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: styrofoam (Thesaurus) Styria Styron Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language