- 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
SynonymsSee more synonyms on Thesaurus.com
- susceptible to impregnation, as an egg.
Origin of impregnable2
Examples from the Web for impregnable
When Sherman reached those earthworks, he thought them the most impregnable he had ever seen.Atlanta’s Fall Foretold The End Of Civil War Bloodshed
September 1, 2014
His place in the hearts of most Thai is central and impregnable.The Real Crisis in Thailand is the Coming Royal Succession
February 22, 2014
But it was really the uemployment data that turned out to be his impregnable fortress.Forget Ohio—September Jobs Report Was Romney’s Undoing
November 7, 2012
She claimed he groped her crotch, pulling at her pantyhose, but the barrier was impregnable.Why Dominique Strauss-Kahn Needs to Tell His Side of the Story
November 28, 2011
In our own single manhood to be bold, Fortressed in conscience and impregnable.'The Grand Old Man
Richard B. Cook
Slowly, cautiously, it was unrolling its ball of impregnable armour.White Fang
The Republic could not suffer at their hands; the Republic and the dynasty were impregnable.The Adventurer
Cyril M. Kornbluth
General von Kluck's artillery was impregnable to the French.
That was, indeed, an impregnable position for any one who knew how to defend it.The Fortune of the Rougons
- unable to be broken into or taken by forcean impregnable castle
- unable to be shaken or overcomeimpregnable self-confidence
- incapable of being refutedan impregnable argument
- able to be impregnated; fertile
Word Origin and History for impregnable
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.