Origin: Latin suffix -able
Unassailable has 5 different meanings across 1 category:
Something, such as a belief, that cannot be assailed.
immune to attack; incapable of being tampered with
"an impregnable fortress"
"fortifications that made the frontier inviolable"
"a secure telephone connection"
impossible to assail
without flaws or loopholes
"an ironclad contract"
"a watertight alibi"
"a bulletproof argument"
Secure against attack; impregnable.