A man-made material consistin' o' glass fibers spun and woven into a mat-like cloth adhered t' a rocket with epoxy resins. It is used t' add strength t' high power rockets, so that they can withstand higher-powered motors than they otherwise could. Although fiberglass is a commonly used word, matey, it is actually a trade mark o' Owen-Cornin' Inc. Avast, me proud beauty! See Pseudo-Glassing