impregnable

Not pregnable; not to be taken or reduced by force: as, an impregnable fortress.

Not to be moved, shaken, or overcome; invincible: as, impregnable virtue.

Not to be stormed, or taken by assault; incapable of being subdued; able to resist attack; unconquerable

Capable of being impregnated, as the egg of an animal, or the ovule of a plant.

Too strong to be penetrated.

Capable of being impregnated.

incapable of being overcome, challenged or refuted

immune to attack; incapable of being tampered with

capable of conceiving