impregnable
adjective
im·preg·na·ble im-ˈpreg-nə-bəl 
1
: incapable of being taken by assault : unconquerable
an impregnable fortress
2
: unassailable
also : impenetrable
impregnable walls
impregnability
(ˌ)im-ˌpreg-nə-ˈbi-lə-tē
noun impregnableness
im-ˈpreg-nə-bəl-nəs
noun impregnably
im-ˈpreg-nə-blē
adverb 
Did you know?
Impregnable is one of the many English words that bear a French ancestry, thanks to the Norman conquest of England in 1066. It derives from the Middle French verb prendre, which means "to take or capture." Combining prendre with various prefixes has given our language many other words, too, including surprise, reprise, and enterprise. Remarkably, impregnable has a different origin from the similar-looking word pregnant; that word comes from a different Latin word, praegnas, meaning "carrying a fetus."
Synonyms
- bulletproof
- indomitable
- insuperable
- insurmountable
- invincible
- invulnerable
- unbeatable
- unconquerable
- unstoppable
See all Synonyms & Antonyms 
Example Sentences
an impregnable fortress that had foiled one invader after another over the centuries the castle's supposedly impregnable walls
Recent Examples on the Web To the Ukrainian soldiers, the plant was a stronghold, surrounded on three sides by water, ringed by high walls, as seemingly impregnable as a medieval keep. 
New York Times, 20 July 2022 Saturday might have seemed perfectly cloudy, with an overcast that seemed impregnable. Martin Weil, Washington Post, 12 June 2022 Ultimately Greenwood and Hanke imagine a United States that’s an autarkic, wholly impregnable island of finance and subsequent economic activity. John Tamny, Forbes, 17 Apr. 2022 That should strike a cautionary note in the executive suites of other companies that seem to hold impregnable positions at the summit of the business world, such as Alphabet (the parent of Google) and Amazon. Michael Hiltzik, Los Angeles Times, 4 Feb. 2022 To be sure, the economic wall around Russia is not impregnable. Washington Post, 18 Mar. 2022 The thick-walled bunker is just one impregnable symbol of resistance and survival, shown with pride in this frigid city, which has already withstood two weeks of Russian ground attacks and sporadic rocket fire. Scott Peterson, The Christian Science Monitor, 14 Mar. 2022 Powered by these two political-economic projects, the Democratic coalition loomed across mid-century American politics as a seemingly impregnable electoral Death Star. Sam Rosenfeld, The New Republic, 15 Feb. 2022 Taylor rushed for 170 yards and one touchdown against the seemingly impregnable New England Patriots defense in a 27-17 victory in Week 15, which moved the Colts toward the front of the A.F.C. wild-card chase. New York Times, 22 Dec. 2021 See More
New York Times, 20 July 2022 Saturday might have seemed perfectly cloudy, with an overcast that seemed impregnable. Martin Weil, Washington Post, 12 June 2022 Ultimately Greenwood and Hanke imagine a United States that’s an autarkic, wholly impregnable island of finance and subsequent economic activity. John Tamny, Forbes, 17 Apr. 2022 That should strike a cautionary note in the executive suites of other companies that seem to hold impregnable positions at the summit of the business world, such as Alphabet (the parent of Google) and Amazon. Michael Hiltzik, Los Angeles Times, 4 Feb. 2022 To be sure, the economic wall around Russia is not impregnable. Washington Post, 18 Mar. 2022 The thick-walled bunker is just one impregnable symbol of resistance and survival, shown with pride in this frigid city, which has already withstood two weeks of Russian ground attacks and sporadic rocket fire. Scott Peterson, The Christian Science Monitor, 14 Mar. 2022 Powered by these two political-economic projects, the Democratic coalition loomed across mid-century American politics as a seemingly impregnable electoral Death Star. Sam Rosenfeld, The New Republic, 15 Feb. 2022 Taylor rushed for 170 yards and one touchdown against the seemingly impregnable New England Patriots defense in a 27-17 victory in Week 15, which moved the Colts toward the front of the A.F.C. wild-card chase. New York Times, 22 Dec. 2021 See More Word History
Etymology
Middle English imprenable, from Middle French, from in- + prenable vulnerable to capture, from prendre to take — more at prize
First Known Use
15th century, in the meaning defined at sense 1
Kids Definition
impregnable
adjective
im·preg·na·ble im-ˈpreg-nə-bəl
: not able to be captured by attack : unconquerable
impregnable
adjective
1
as in invincible
incapable of being defeated, overcome, or subdued an impregnable fortress that had foiled one invader after another over the centuries Synonyms & Similar Words
Relevance
- invincible
- invulnerable
- unconquerable
- insurmountable
- bulletproof
- unstoppable
- unbeatable
- indomitable
- unassailable
- armored
- insuperable
- undefeated
- inviolable
- unbreachable
- guarded
- untouchable
- protected
- defended
- secure
- safeguarded
- shielded
- unbeaten
- unconquered
- safe
- unbowed
- unsubdued
Antonyms & Near Antonyms
- vulnerable
- unprotected
- susceptible
- unguarded
- vincible
- insecure
- weak
- unsafe
- open
- surmountable
- liable
- helpless
- powerless
- defenseless
- imperiled
- exposed
- imperilled
- superable
2
as in impenetrable
impossible to get through or into the castle's supposedly impregnable walls Synonyms & Similar Words
- impenetrable
- dense
- impervious
- close
- sturdy
- impassable
- impermeable
- thick
- impassible
- compact
- tight
- solid
- substantial
- compressed
- tough
- frozen
- condensed
- rigid
- hard
- inflexible
- firm
- unyielding
- stiff
- unbending
Antonyms & Near Antonyms
- permeable
- soft
- passable
- negotiable
- penetrable
- elastic
- flexible
- giving
- malleable
- porous
- pliable
- yielding
- squishy
- absorbent
- bendable