[1] : The Collaborative International Dictionary of English v.0.48

unassailable \unassailable\
   see assailable.
see also:
assailable 

[2] : WordNet (r) 2.0

unassailable
     adj 1: able to withstand attack; "an impregnable fortress";
            "fortifications that made the frontier inviolable"
            syn: impregnable, inviolable, secure, strong,
             unattackable
     2: impossible to assail syn: untouchable
     3: without flaws or loopholes; "an ironclad contract"; "a
        watertight alibi"; "a bulletproof argument" syn: ironclad,
         unshakable, watertight, bulletproof
see also:
impregnable inviolable secure strong unattackable untouchable 
ironclad unshakable watertight bulletproof 

[3] : Moby Thesaurus II by Grady Ward, 1.0

18 moby thesaurus words for "unassailable":
   impenetrable, impregnable, incontestable, indomitable,
   inexpugnable, insuperable, invincible, inviolable, invulnerable,
   irresistible, overpowering, overwhelming, resistless, unbeatable,
   unconquerable, unsubduable, unsurmountable, unyielding

Unassailable >> U Words
Unassailable, definition of term: Unassailable
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