|a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.|
|the offspring of a zebra and a donkey.|
|polystyrene (pŏl'ē-stī'rēn) Pronunciation Key
A brittle synthetic polymer composed of repeated styrene units. Polystyrene is transparent and rigid because the benzene rings in each styrene unit prevent the polystyrene chains from arranging themselves into a tight crystalline structure. Polystyrene has a wide variety of uses, especially as a solid foam for insulation and packaging.
an important member of the class of synthetic organic polymers, composed of long-chain molecules prepared by a chemical reaction in which many (usually 2,000-3,000) molecules of the aromatic hydrocarbon styrene become linked together.
Learn more about polystyrene with a free trial on Britannica.com.