Synonyms: unassailable, bulletproof, unshakable, watertight
Definition: without flaws or loopholes
Usage: an ironclad contract; a watertight alibi; a bulletproof argument
Similar words: incontestable, incontestible
Definition: incapable of being contested or disputed
Synonyms: untouchable, unassailable
Definition: impossible to assail
Similar words: inviolable
Definition: incapable of being transgressed or dishonored
Usage: the person of the king is inviolable; an inviolable oath
Synonyms: 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
Similar words: invulnerable
Definition: immune to attack; impregnable
Usage: gunners raked the beach from invulnerable positions on the cliffs