DICT.TW Dictionary Taiwan

 Im·preg·na·ble a.  Not to be stormed, or taken by assault; incapable of being subdued; able to resist attack; unconquerable; as, an impregnable fortress; impregnable virtue.
    The man's affection remains wholly unconcerned and impregnable.   --South.
 -- Im*preg*na*ble*ness, n. -- Im*preg*na*bly, adv.

 impregnably
      adv : in an impregnable manner; "the sight of that bland,
            impregnably righteous face has been enough to make
            their blood run cold"