impregnable Definition

unassailable, invulnerable, unconquerable, inviolable, secure, strong, inexpugnable, unattackable, fortified, citadel, inaccessible, spectacular, nigh, brass, impenetrable, invincible, indestructible, unshakable, unshakeable, undefeatable, unbreakable, formidable, assailable, unstoppable, unbeatable, impervious, inviolate, immovable, watertight, unmovable, insurmountable, penetrable, bulletproof, infallible, obdurate, fearsome, unchallengeable, impermeable, ironclad, indomitable, bombproof, unyielding, insuperable, resolute, undefended, unsurpassable, unshaken, sacrosanct, undefendable, unflappable, implacable, irremovable, redoubtable, foolproof, irresistible, untouchable, unclimbable, defensive structure, porous, immoveable, unbridgeable, propugnacle, imperious, untroubled, unscalable, unbendable, unthinkable, vaunted, impotent, crenellated, unvanquished, nerveless, brittle, unassailed, airtight, unflustered, peerless, unsusceptible, unattainable, imperturbable, flawless, unquestioned, fortifiable, beatable, unbroken, unfathomable, vincible, inconceivable, sturdiest, untenable, faultless, afforcement, moated, sandbagged, mortal, entrenched, embattail, stout, irresistable, magnificent,