Home › Words › P › prepregprepregprepreg means fiber material impregnated with its matrix material, usually a plastic, well before its use to form a manufactured part.EtymologyClipping of pre-impregnated.nounFiber material impregnated with its matrix material, usually a plastic, well before its use to form a manufactured part.Definitions & examples from Wiktionary (CC BY-SA 3.0).