1
: made of cast iron
2
: resembling cast iron: such as
a
: capable of withstanding great strain
a cast-iron stomach
b
: not admitting change, adaptation, or exception : rigid
a cast-iron will
c
British
: not likely to fail or be broken : airtight
"Clever idea, Black, getting yourself seen on a safe station platform … gave you a cast-iron excuse not to leave your hidey-hole in future, didn't it?"—
J. K. Rowling
J. K. Rowling
: a commercial alloy of iron, carbon, and silicon that is cast in a mold and is hard, brittle, nonmalleable, and incapable of being hammer-welded but more easily fusible than steel
Examples of cast-iron in a Sentence
Adjective
lost weight only after a cast-iron adherence to his diet
he has a cast-iron faith in his innate ability to overcome any adversity that life might throw against him
Noun
The fence is made of cast iron.
Recent Examples on the Web
Melanie Fincher, Southern Living, 10 July 2025
Carbon discs are drilled with holes for thermal regulation, while cast-iron discs, which take a little longer to cool, are vaned for air flow.
—Kristin Shaw, ArsTechnica, 10 July 2025
Dana Afana, Freep.com, 12 July 2025
Le Creuset Enameled Cast Iron Skillet This cast iron skillet is durable, versatile, and perfect for everything from searing steaks to baking biscuits — and my personal favorite?
—Jeaneen Russell, People.com, 8 July 2025
See All Example Sentences for cast-iron
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Adjective
Expect Southern Living-tested finds like our go-to cast-iron skillet, cooling bedding made for Southern summers, and more—up to 50% off, but only through tomorrow.
—Melanie Fincher, Southern Living, 10 July 2025
Carbon discs are drilled with holes for thermal regulation, while cast-iron discs, which take a little longer to cool, are vaned for air flow.
—Kristin Shaw, ArsTechnica, 10 July 2025
Noun
Residents filed the lawsuit a day before Detroit's Historic District Commission voted to proceed with a revised version of the project, which includes using cast iron manhole covers instead of steam vent stacks.
—Dana Afana, Freep.com, 12 July 2025
Le Creuset Enameled Cast Iron Skillet This cast iron skillet is durable, versatile, and perfect for everything from searing steaks to baking biscuits — and my personal favorite?
—Jeaneen Russell, People.com, 8 July 2025
See All Example Sentences for cast-iron
Cite this Entry
“Cast-iron.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cast-iron. Accessed 19 Jul. 2025.
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