bʊl.ɪtpɹuːf ˈstɛdfæst ˈstɛdi

stɪf ˌʌnəˈseɪləbl̩ ˈwɔː.tə.taɪt without flaws or loopholes an ironclad contract a watertight alibi a bulletproof argument marked by firm determination or resolution; not shakable firm convictions a firm mouth steadfast resolve a man of unbendable perseverance unwavering loyalty