ironclad

The old gate was covered with thick metal plates for extra security.

古い門は追加の安全のために厚い金属板で覆われていた。

an ironclad guarantee

絶対的な保証。

They studied the 19th-century vessel that was shielded with metal armour.

彼らは金属の装甲で覆われた19世紀の船を調べた。