cast-iron

cast-iron
ˌcast-ˈiron adjective
1. a cast-iron excuse/alibi/guarantee etc an excuse etc that is very certain and cannot fail
2. made of cast iron:
    a cast-iron frying pan

cast-ironBrE /ˌkɑːst ˈaɪən/ 🔊NAmE /ˌkæst ˈaɪərn/ 🔊 adjectivemade of cast iron 铸铁制的◆a cast-iron bridge铸铁桥(BrE) very strong or certain; that cannot be broken or fail 有力的；确实的；坚定不移的◆a cast-iron guarantee/promise 永不反悔的保证；铁誓◆a cast-iron excuse/alibi 有说服力的辩解；不在犯罪现场的确凿证据  ➡  compare ironclad