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[im-preg-nuh-buh l] /ɪmˈprɛg nə bəl/
strong enough to resist or withstand attack; not to be taken by force, unconquerable:
an impregnable fort.
not to be overcome or overthrown:
an impregnable argument.
Origin of impregnable1
late Middle English
1400-50; late Middle English impregnable, imprenable < Middle French, equivalent to im- im-2 + prenable pregnable
Related forms
impregnability, impregnableness, noun
impregnably, adverb
1. invulnerable. 1, 2. See invincible. 2. unassailable.
1. vulnerable. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for impregnability
Contemporary Examples
Historical Examples
  • They had spent the winter in (p. 120) adding to what nature had made nearly perfect—the impregnability of the entire sector.

  • If any spot can impress the notion of impregnability it is Kuffstein.

  • Of course his impregnability gave rise to all manner of stories.

    The New Tenant E. Phillips Oppenheim
  • I know they would; after Liege and Namur one knows that modern guns can outlaw any impregnability of the past.

    The Spell of Scotland Keith Clark
  • The time came, however, when the ramparts we scaled rose sheer and bare in impregnability.

    The Forest Stewart Edward White
  • The castle profited by the road in accessibility, but its impregnability was so far lessened.

    The Dove in the Eagle's Nest Charlotte M. Yonge
  • Probably that was Martin Jaffry's own impregnability—that he wouldn't have lied about a lady to save himself.

    The Sturdy Oak Samuel Merwin, et al.
  • Each visit to Thermopyl has, however, deepened my conviction that Herodotus exaggerated the impregnability of this pass.

    Vacation days in Greece Rufus B. Richardson
  • In Roman times the site still held its own as one of importance and impregnability.

British Dictionary definitions for impregnability


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
Derived Forms
impregnability, impregnableness, noun
impregnably, adverb
Word Origin
C15 imprenable, from Old French, from im- (not) + prenable able to be taken, from prendre to take


able to be impregnated; fertile
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for impregnability



early 15c., imprenable "impossible to capture," from Middle French imprenable "invulnerable," from assimilated form of in- "not, opposite of" (see in- (1)) + Old French prenable "assailable, vulnerable" (see pregnable). With intrusive -g- 16c., on model of deign, reign, etc. Related: Impregnability.

Online Etymology Dictionary, © 2010 Douglas Harper
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