UPVCUPVC, uPVC /ˌjuː piː viː ˈsiː/ noun [uncountable] 
(unplasticized polyvinyl chloride) a type of plastic, used especially to make window frames: 
UPVC double-glazed windows
(unplasticized polyvinyl chloride) a type of plastic, used especially to make window frames: UPVC double-glazed windows