impregnable

UK: /ɪmˈprɛgnəb^əl/ US: /ɪmˈprɛgnəbəl/ ,(im preg′nə bəl)

WordReference Random House Learner's Dictionary of American English © 2025

im•preg•na•ble¹ /ɪmˈprɛgnəbəl/   adj. 

1. strong enough to withstand attack; unconquerable:
   an impregnable fort.
2. that cannot be argued against or shown to be wrong:
   impregnable proof.

im•preg•na•bil•i•ty /ɪmˌprɛgnəˈbɪlɪti/  n. [uncountable]
im•preg•na•bly, adv. 

im•preg•na•ble² /ɪmˈprɛgnəbəl/   adj. 

1. Developmental Biology that may become pregnant.

WordReference Random House Unabridged Dictionary of American English © 2025

im•preg•na•ble¹  (im preg′nə bəl), adj. 

1. strong enough to resist or withstand attack;
   not to be taken by force, unconquerable:
   an impregnable fort.
2. not to be overcome or overthrown:
   an impregnable argument.

• Middle French, equivalent. to im- im-² + prenable pregnable
• late Middle English impregnable, imprenable 1400–50

im•preg′na•bil′i•ty, im•preg′na•ble•ness, n. 
im•preg′na•bly, adv. 
Synonyms

• 1. invulnerable.
• 1, 2. See invincible. 
• 2. unassailable.

Antonyms

• 1. vulnerable.

im•preg•na•ble²  (im preg′nə bəl), adj. 

1. Developmental Biology susceptible to impregnation, as an egg.

• impregn(ate) + -able

Collins Concise English Dictionary © HarperCollins Publishers::

impregnable / ɪmˈprɛɡnəb^əl/ adjective

1. unable to be broken into or taken by force: an impregnable castle
2. unable to be shaken or overcome: impregnable self-confidence
3. incapable of being refuted: an impregnable argument

Etymology: 15th Century imprenable, from Old French, from im- (not) + prenable able to be taken, from prendre to take

imˌpregnaˈbility, imˈpregnableness noun

imˈpregnably adverb

impregnable / ɪmˈprɛɡnəb^əl/, impregnatable / ˌɪmprɛɡˈneɪtəb^əl/ adjective

1. able to be impregnated; fertile