fibreglass /ˈfaɪbəɡlɑːs/noun 3verb 1forms 3 noun3 •Silica based glass extruded into fibers that possess a length at least 1000 times greater than their width. •A composite material made from fine fibres of spun glass held together with resin. •Ellipsis of fibreglass wool. verb1 •To apply fibreglass to. formsfibreglassed · fibreglassing · fibreglasses