Main entry: unassailable, bulletproof, unshakable, watertight
Definition: without flaws or loopholes
Usage: an ironclad contract; a watertight alibi; a bulletproof argument
Main entry: untouchable, unassailable
Definition: impossible to assail
Main entry: inviolable, impregnable, unassailable, unattackable, strong, secure
Definition: immune to attack; incapable of being tampered with
Usage: an impregnable fortress; fortifications that made the frontier inviolable; a secure telephone connection