bʊl.ɪtpɹuːf bʊl.ɪtpɹuːf ˌʌnəˈseɪləbl̩ ˈwɔː.tə.taɪt not penetrable by bullets bulletproof glass bulletproof vest make bulletproof bulletproof the car without flaws or loopholes an ironclad contract a watertight alibi a bulletproof argument