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

Tier 2 isn’t quite as ironclad as the top group, but nobody will think twice if any of UConn, Duke, Houston or Illinois cuts down the nets in April. —Brendan Marks, New York Times, 12 Feb. 2026

Her love songs have always had a strong current of devotion, but her conviction here is ironclad, her voice clarion rather than yearning. —Stephen Kearse, Pitchfork, 11 Feb. 2026

Noun

Today the bag is still made with the same ironclad material used in conveyor belts. —Jessica Sulima, Condé Nast Traveler, 14 Dec. 2025

In September of this year, Trump suggested that the United States could deploy additional rotational forces to Poland, signaling ironclad resolve against Russian revanchism. —Robert C. O’Brien, Foreign Affairs, 5 Nov. 2025

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