impregnable

impregnable
    adj 1: immune to attack; incapable of being tampered with; "an
           impregnable fortress"; "fortifications that made the
           frontier inviolable"; "a secure telephone connection"
           [syn: {impregnable}, {inviolable}, {secure}, {strong},
           {unassailable}, {unattackable}]
    2: capable of conceiving [syn: {conceptive}, {impregnable}]
    3: incapable of being overcome, challenged or refuted; "an
       impregnable argument"; "impregnable self-confidence" [syn:
       {impregnable}, {inexpugnable}]
    

Impregnable \Im*preg"na*ble\, a. [F. imprenable; pref. im- not +
   prenable pregnable, fr. prendre to take, L. prehendere. See
   {Comprehend}, {Get} to obtain.]
   Not to be stormed, or taken by assault; incapable of being
   subdued; able to resist attack; unconquerable; as, an
   impregnable fortress; impregnable virtue.
   [1913 Webster]

         The man's affection remains wholly unconcerned and
         impregnable.                             --South.
   -- {Im*preg"na*ble*ness}, n. -- {Im*preg"na*bly}, adv.
   [1913 Webster]
    

Impregnable \Im*preg"na*ble\, a. [See Impregnate.] (Biol.)
   Capable of being impregnated, as the egg of an animal, or the
   ovule of a plant.
   [1913 Webster]
    

42 Moby Thesaurus words for "impregnable":
      deathless, defended, guarded, immortal, impenetrable, imperishable,
      incontestable, incorruptible, indelible, indestructible,
      indomitable, ineffaceable, ineradicable, inexpugnable,
      inextinguishable, insuperable, invincible, inviolable,
      invulnerable, irresistible, mighty, nonperishable, overpowering,
      overwhelming, protected, quenchless, resistless, safe, safeguarded,
      secure, shielded, unassailable, unbeatable, unconquerable,
      undampable, undefeatable, undestroyable, undying, unquenchable,
      unsubduable, unsurmountable, unyielding