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.
Infantino has clashed with players' unions and European football, but he remains in an impregnable position at the top of the world game.
From BBC • Feb. 25, 2026
“Some criminals have understood that museums are not impregnable cultural fortresses,” said Pierre Noual, a French lawyer specializing in cultural heritage law.
From The Wall Street Journal • Nov. 13, 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
“It’s like hitting a bullet with a bullet,” someone says, crushing the naive notion of an impregnable “nuclear defense.”
From Los Angeles Times • Oct. 9, 2025
Satisfied that the door was now impregnable I then scuttled back to the bedroom and there leaped onto the bed by the latticed window.
From "Kaffir Boy: An Autobiography" by Mark Mathabane
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.
