cast-iron

1 of 2

adjective

ˈkast-ˈī(-ə)rn 

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

cast iron

2 of 2

noun

: 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

Synonyms of cast-iron

Adjective

• strict
• rigorous
• rigid

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

Adjective

Ribbons of roses curl up the sides of the lights along 6th Street, Chinese dragons hang from the lamps on Olympic Boulevard, and topless women watch over Wilshire Boulevard from their cast-iron perches. —Los Angeles Times, 8 May 2026

Its distinctive mansard roof, cast-iron details and granite columns reflected the optimism of the post-Civil War era, and stand out next to its neighboring neoclassical buildings. —Rachel Treisman, NPR, 4 May 2026

Noun

It is made of durable cast iron but features a smooth enamel interior that keeps food from sticking. —Bestreviews, Chicago Tribune, 4 May 2026

This includes metals like cast iron, and stainless steel. —Ashlyn Needham, Southern Living, 4 May 2026

Word History

First Known Use

Adjective

1692, in the meaning defined at sense 1

Noun

1664, in the meaning defined above

Rhymes for cast-iron

• aileron
• antiphon
• autobahn
• carillon
• castellan
• celadon
• cephalon
• chitosan
• cynodon
• denouement
• deuteron
• echelon

Kids Definition

cast iron

noun

: a hard brittle alloy of iron, carbon, and silicon shaped by being poured into a mold while melted