I. fi ‧ ber ‧ glass /ˈfaɪbəɡlɑːs $ -bərɡlæs/ BrE AmE noun [uncountable]
the American spelling of ↑ fibreglass
II. fi ‧ bre ‧ glass BrE AmE British English , fiberglass American English /ˈfaɪbəɡlɑːs $ -bərɡlæs/ noun [uncountable]
a light material made from small glass threads pressed together, used for making sports cars, small boats etc