The Collaborative International Dictionary
Pregnable \Preg"na*ble\, a., [F. prenable. See Impregnable.]
Capable of being entered, taken, or captured; expugnable; as,
a pregnable fort. [R.]
--Cotgrave.
Douglas Harper's Etymology Dictionary
1530s, alteration of Middle English preignable, earlier prenable (early 15c.), from Old French prenable "assailable, vulnerable," from stem of prendre "to take, grasp, seize," from Latin prehendere "to take hold of, to seize" (see prehensile).
Wiktionary
a. vulnerable to attack
Usage examples of "pregnable".
The very size and bulk of the walls were repugnant to the Valemen, who preferred the freedom o the more pregnable forest lands surrounding their own home, but exhaustion quickly pushed any dislikes aside and they passed without hesitating through the west gates and into the narrow streets of the city.
He did not, he simply could not believe that his base was as pregnable as the coordinator had assumed it to be.
There is a nourishing sense of pregnable space in a big indoor club that you never get playing outside, especially playing outside in the cold, when the balls feel hard and sullen and come off the stick's strung face with an echoless ping.