impregnable
1 Americanadjective
-
strong enough to resist or withstand attack; not to be taken by force, unconquerable.
an impregnable fort.
- Synonyms:
- invulnerable
- Antonyms:
- vulnerable
-
not to be overcome or overthrown.
an impregnable argument.
- Synonyms:
- unassailable
adjective
adjective
-
unable to be broken into or taken by force
an impregnable castle
-
unable to be shaken or overcome
impregnable self-confidence
-
incapable of being refuted
an impregnable argument
adjective
Related Words
See invincible.
Other Word Forms
- impregnability noun
- impregnableness noun
- impregnably adverb
Etymology
Origin of impregnable1
First recorded in 1400–50; late Middle English impregnable, imprenable, from Middle French, equivalent to im- im- 2 + prenable pregnable
Origin of impregnable2
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
In theory that threatens Apple’s impregnable walled garden.
From The Wall Street Journal • Jan. 2, 2026
In 2015, the seemingly impregnable Central Belt – and beyond – in Scotland fell to the Scottish National Party from Labour.
From BBC • Dec. 30, 2025
Singapore was considered impregnable, but it wasn’t prepared for an attack from the mainland, and its 60,000-strong garrison surrendered on Feb. 8, 1942, the worst defeat in British history.
From The Wall Street Journal • Oct. 27, 2025
High-flying Crystal Palace are the only side to rival City's attacking threat, while Newcastle are living up to their name by being almost as impregnable at the back as Arsenal.
From BBC • Oct. 15, 2025
The castle’s front entrance, which had been impregnable for so many years, swung open as Sorrento approached, like an automatic door at a supermarket.
From "Ready Player One: A Novel" by Ernest Cline
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
