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.
China has also invested billions into infrastructure projects in Pakistan as part of President Xi Jinping's Belt and Road initiative and the two governments call themselves "ironclad brothers."
From Barron's • Apr. 10, 2026
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
In 2019, Stanford University anesthesiologist Boris Heifets and his colleagues began the most ironclad blinded study yet attempted in the psychedelics world.
From Slate • Jan. 30, 2026
Board members said they were concerned that Paramount’s financing appeared shaky and the Ellison family’s assurances were far from ironclad.
From Los Angeles Times • Dec. 17, 2025
One of Momma Biles’s ironclad rules was that no matter where we were or what we were doing, once the streetlights came on, it was time to head home.
From "Courage to Soar" by Simone Biles
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.
