#1 unassailable s. [impregnable, inviolable, secure, strong, unattackable] immune to attack; incapable of being tampered with; "an impregnable fortress"; "fortifications that made the frontier inviolable"; "a secure telephone connection". wn
#2 unassailable s. [untouchable] impossible to assail. wn
#3 unassailable s. [unshakable, watertight, bulletproof] without flaws or loopholes; "an ironclad contract"; "a watertight alibi"; "a bulletproof argument". wn
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