Adjective: unassailable ,ún-u'sey-lu-bul
- Impossible to challenge successfully
"The champion's record seemed unassailable";
- untouchable
- Immune to attack; incapable of being tampered with
"an unassailable fortress";
- impregnable [rare], inviolable, secure, strong, unattackable
- Without flaws or loopholes
"Her unassailable logic won the debate";
- unshakable, watertight, bulletproof, ironclad, unshakeable
See also: incontestable, incontestible, inviolable, invulnerable, irrefrangible