definition of
unassailable

[1] #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] #2 unassailable s. [untouchable] impossible to assail. wn

[3] #3 unassailable s. [unshakable, watertight, bulletproof] without flaws or loopholes; "an ironclad contract"; "a watertight alibi"; "a bulletproof argument". wn