Im‐preg″na‐ble (?), a. [F. imprenable; pref. im- not + prenable pregnable, fr. prendre to take, L. prehendere. See Comprehend, Get to obtain.] 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.