Ironclad
来自Big Physics
Safin（讨论 | 贡献）2022年4月28日 (四) 04:47的版本 （建立内容为“Category:etymology == wiktionary == [https://en.wiktionary.org/wiki/ironclad ref] From iron + clad. == etymonline == [https://www.etymonline.com/word…”的新页面）
wiktionary
From iron + clad.
etymonline
ironclad (adj.)
1852 of knights, 1861, of warships, American English, from iron (n.) + clad. Figuratively, of contracts, etc., "very rigid or strict, allowing no evasion or escape," from 1884. As a noun meaning "iron-clad ship," it is attested from 1862.
