Im-prĕg'na-ble, a.
a. [Prefix im, not, and pregnable; Fr. imprenable, Pr. imprenable, emprenable.]
Sense 1. Not to be stormed, or taken by assault; incapable of being reduced by force; able to resist attack; as, an impregnable fortress.
Sense 2. Not to be moved, impressed, or shaken; invincible.
The man's affection remains wholly unconcerned and impregnable. South.