ironclad

US: /adj. ˈaɪɚnˈklæd; n. -ˌklæd/

US: (adj. ī′ərn klad′; n. ī′ərn klad′)

WordReference Random House Learner's Dictionary of American English © 2025

i•ron•clad /adj. ˈaɪɚnˈklæd; n. -ˌklæd/   adj. 

1. Nautical, Naval Terms covered with iron plates, as a vessel;
   armor-plated.
2. inflexible;
   unbreakable:
   an ironclad contract.

n. [countable]

3. Nautical, Naval Terms a wooden warship of the middle or late 19th century having iron or steel armor plating.

WordReference Random House Unabridged Dictionary of American English © 2025

i•ron•clad  (adj. ī′ərn klad′;n. ī′ərn klad′), adj. 

1. Nautical, Naval Terms covered or cased with iron plates, as a ship for naval warfare;
   armor-plated.
2. very rigid or exacting;
   inflexible;
   unbreakable:
   an ironclad contract.

n. 

3. Nautical, Naval Terms a wooden warship of the middle or late 19th century having iron or steel armor plating.

• iron + clad¹ 1850–55

Collins Concise English Dictionary © HarperCollins Publishers::

ironclad adjective / ˌaɪənˈklæd/

1. covered or protected with iron: an ironclad warship
2. inflexible; rigid: an ironclad rule

noun / ˈaɪənˌklæd/

1. a large wooden 19th-century warship with armoured plating