pregnable (adj.)

of a fortress, etc., "capable of being taken or won by force," 1530s, an alteration of Middle English preignable, earlier prenable (early 15c.), pernable (late 14c.), from Old French prenable, pregnauble "assailable, vulnerable," from stem of prendre "to take, grasp, seize," from Latin prehendere "to take hold of, to seize" (from prae- "before," see pre-, + -hendere, from PIE root *ghend- "to seize, take"). The form was confused in French and English by the influence of unrelated words from French preignaunt and English pregnant.