ironclad

1 of 2

adjective

iron·​clad ˈī(-ə)rn-ˈklad 

1

: sheathed in iron armor

—used especially of naval vessels

2

: so firm or secure as to be unbreakable: such as

a

: binding

an ironclad oath

b

: having no obvious weakness

an ironclad case against the defendant

ironclad

2 of 2

noun

iron·​clad ˈī(-ə)rn-ˌklad 

: an armored naval vessel especially of the mid to late 19th century

Examples of ironclad in a Sentence

Adjective

The company has an ironclad policy against revealing secrets to competitors.

He has an ironclad alibi.

Recent Examples on the Web

Adjective

But experts have worried that doctors are hesitating to offer treatment without an ironclad diagnosis, which clinicians say can take time and increase risks to the mother. — Andrea Suozzo, ProPublica, 9 Sep. 2026

The trend poses a challenge to Trump, whose grip on the Republican brand has been ironclad for over a decade. — Los Angeles Times, 9 Sep. 2026

Noun

Israel, for its part, enjoyed the most ironclad of American security guarantees. — Marc Lynch, Foreign Affairs, 18 Aug. 2026

The Confederate ironclad Tennessee patrolled the bay, and Fort Morgan and Fort Gaines stood sentry over the entrance. — Encyclopedia Britannica, 18 Aug. 2026

Word History

First Known Use

Adjective

circa 1847, in the meaning defined at sense 1

Noun

1862, in the meaning defined above

Rhymes for ironclad

• cephalad
• galahad
• libertad
• undergrad
• ad
• add
• bad
• brad
• cad
• clad
• dad
• fad

Kids Definition

ironclad

1 of 2 adjective

iron·​clad -ˈklad 

1

: covered by iron armor

2

: rigorous sense 1, exacting

ironclad laws

ironclad

2 of 2 noun

iron·​clad -ˌklad 

: an armored naval vessel