cast iron

¹ American  

noun

1. an alloy of iron, carbon, and other elements, cast as a soft and strong, or as a hard and brittle, iron, depending on the mixture and methods of molding.

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cast-iron ² American  

[kast-ahy-ern, kahst-] / ˈkæstˈaɪ ərn, ˈkɑst- /

adjective

1. made of cast iron.

2. not subject to change or exception.

   a cast-iron rule.

3. hardy.

   a cast-iron stomach.

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cast iron British  

noun

1. iron containing so much carbon (1.7 to 4.5 per cent) that it cannot be wrought and must be cast into shape

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adjective

1. made of cast iron

2. rigid, strong, or unyielding

   a cast-iron decision

Etymology

Origin of cast iron¹

1655–65; cast (past participle of cast ( def. ) ) + iron

Origin of cast-iron²

First recorded in 1655–65

Example Sentences

The snake and cast iron plant can also tolerate darker areas in your home.

From BBC • Jan. 14, 2026

He called on Lammy to give his "cast iron assurance" that Kebatu will be deported from the country by the end of the week.

From BBC • Oct. 27, 2025

Adjoining stores sold cast iron skillets, toys and old-fashioned candies, with rocking chairs out front for waiting customers.

From The Wall Street Journal • Oct. 25, 2025

Le Creuset, which celebrates 100 years of business this year, is a French cookware brand known for its expertly crafted cast iron products available in a multitude of colorways.

From Salon • Sep. 23, 2025

I’d gotten him some cooking supplies—an apron embroidered with “Big Tomato,” my nickname for him, and a nice cast iron pan.

From "From the Desk of Zoe Washington" by Janae Marks