Definition of "styrofoam"

A while ago I read your column concerning the effects of hot tea on styrofoam cups.

1988 November 4, Cecil Adams, “The Straight Dope”, in Chicago Reader‎

In the past two years, NASA’s Kepler Space Telescope has located nearly 3,000 exoplanet candidates ranging from sub-Earth-sized minions to gas giants that dwarf our own Jupiter. Their densities range from that of styrofoam to iron.

2013 May-June, Kevin Heng, “Why Does Nature Form Exoplanets Easily”, in American Scientist, volume 101, number 3, page 184

Expanded polystyrene foam—commonly, although incorrectly, called Styrofoam—has been the subject of a protracted battle between New York City officials and large industry players, particularly Dart.

2018 August 9, Gerald Porter Jr., Corinne Ramey, “Industry-Backed Group Keeps Fighting Foam Ban”, in The Wall Street Journal