Not to be stormed, or taken by assault; incapable of being subdued; able to resist attack; unconquerable; as, an impregnable fortress; impregnable virtue.(adjective)
source: webster1913
Capable of being impregnated, as the egg of an animal, or the ovule of a plant.(adjective)
source: webster1913
adjective satellite (s)
immune to attack; incapable of being tampered with(adj.all)