iron·​clad | \ ˈī(-ə)rn-ˈklad How to pronounce ironclad (audio) \

Definition of ironclad

 (Entry 1 of 2)

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


iron·​clad | \ ˈī(-ə)rn-ˌklad How to pronounce ironclad (audio) \

Definition of ironclad (Entry 2 of 2)

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

Examples of ironclad in a Sentence


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

Recent Examples on the Web: Adjective

But Puerto Rico’s constitution stipulates that its separate general obligation bonds have first dibs on available government resources, raising doubt as to whether the Cofina bonds were truly ironclad. Andrew Scurria, WSJ, "Puerto Rico Bondholders Agree on Sales-Tax Split," 8 Aug. 2018 The supposedly ironclad audits KPMG had performed quickly fell under suspicion. New York Times, "Corruption Gutted South Africa’s Tax Agency. Now the Nation Is Paying the Price.," 10 June 2018 Washington’s second leadership posture was ironclad emotional control. Sam Walker, WSJ, "The Two Contagious Behaviors of a Great Boss," 22 Sep. 2018 But California would retain ironclad control over its own clean energy policies. David Roberts, Vox, "California’s huge energy decision: link its grid to its neighbors, or stay autonomous?," 23 Aug. 2018 In the ensuing years, the Castros ruled over Cuba with ironclad control, bolstered by a cadre of loyalists, nearly all of whom had fought alongside them in the revolution. Azam Ahmed And Frances Robles, New York Times, "Who Is Miguel Díaz-Canel, Cuba’s New President?," 19 Apr. 2018 The Deep South initially demanded slavery’s ironclad protection. David S. Reynolds, WSJ, "‘No Property in Man’ and ‘The War Before the War’ Review: The Fuse the Founders Lit," 22 Nov. 2018 In one key shift, investors realized bonds backed by a municipality’s full faith and credit weren’t as ironclad as once thought, because pensioners received priority over some bondholders in the court battle over limited government funds. Gunjan Banerji, WSJ, "Detroit Sees Big Demand in Muni Market Return," 4 Dec. 2018 Of course, Star Wars has an ironclad reason for bringing back dead characters, known as Force Ghosts. Adam Schubak, Popular Mechanics, "Everything We Know So Far About Star Wars Episode IX," 17 Sep. 2018

Recent Examples on the Web: Noun

During the Civil War, Eads won a contract to build Union ironclads. Mike Scott,, "Meet the man who tamed the Mississippi -- and saved the port of New Oreans," 1 May 2018 In 1862, during the Civil War, the ironclads USS Monitor and CSS Virginia (formerly USS Merrimac) clashed for five hours to a draw at Hampton Roads, Va., "This day in history," 9 Mar. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ironclad.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of ironclad


circa 1847, in the meaning defined at sense 1


1862, in the meaning defined above

Keep scrolling for more

Learn More about ironclad

Statistics for ironclad

Last Updated

8 May 2019

Look-up Popularity

Time Traveler for ironclad

The first known use of ironclad was circa 1847

See more words from the same year

Keep scrolling for more

More Definitions for ironclad



English Language Learners Definition of ironclad

: not able to be changed
: too strong to be doubted or questioned

Keep scrolling for more

More from Merriam-Webster on ironclad

Rhyming Dictionary: Words that rhyme with ironclad

Spanish Central: Translation of ironclad

Nglish: Translation of ironclad for Spanish Speakers Encyclopedia article about ironclad

Comments on ironclad

What made you want to look up ironclad? Please tell us where you read or heard it (including the quote, if possible).


standardized text or formulaic language

Get Word of the Day daily email!

Test Your Vocabulary

Finance Words Quiz

  • a-piggy-bank
  • The etymology of mortgage is related most closely to which two words?
True or False

Test your knowledge - and maybe learn something along the way.


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!