ironclad
Americanadjective
-
covered or cased with iron plates, as a ship for naval warfare; armor-plated.
-
very rigid or exacting; inflexible; unbreakable.
an ironclad contract.
noun
adjective
-
covered or protected with iron
an ironclad warship
-
inflexible; rigid
an ironclad rule
-
not able to be assailed or contradicted
an ironclad argument
noun
Etymology
Origin of ironclad
Explanation
Something ironclad is either covered in iron for protection or protected in a different way. An ironclad guarantee can’t be broken or taken back. Originally, this word was very literal: an ironclad battleship was clad (covered) in iron. Since then, this word is more metaphorical, though it still applies to things you can trust. An ironclad contract is unbreakable. An ironclad promise can be believed wholeheartedly. If you were arrested on ironclad charges, you’re going to be found guilty.
Vocabulary lists containing ironclad
The American Civil War
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President Trump's First State of The Union Address (2018)
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Courage to Soar
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Nvidia’s next earnings report in November made it clear the $100 billion figure wasn’t exactly an ironclad commitment.
From MarketWatch • Feb. 1, 2026
Even if bubble fears are misplaced—remember, statistical observations are just that, not ironclad predictions—this trend is still noteworthy.
From Barron's • Dec. 10, 2025
Its defense agreement fell short of the ironclad mutual-defense pact it wants.
From The Wall Street Journal • Nov. 21, 2025
But if they don’t include ironclad provisions outlawing impoundment under all circumstances, those concessions won’t be worth the paper they’re printed on.
From Slate • Sep. 10, 2025
That was not, of course, an ironclad promise, but he would accomplish it literally.
From "One Hundred Years of Solitude" by Gabriel Garcia Marquez
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
