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

ironclad \i"ronclad`\, a.
   1. clad in iron; protected or covered with iron, as a vessel
      for naval warfare.
      1913 webster

   2. rigorous; unbreakable; severe; exacting; inflexible; as,
      an ironclad oath or pledge. colloq.
      1913 webster

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

ironclad \i"ronclad`\, n.
   a naval vessel having the parts above water covered and
   protected by iron or steel usually in large plates closely
   joined and made sufficiently thick and strong to resist heavy
   shot. modern naval vessels are made of steel throughout, and
   this term is only used in historical contexts.
   1913 webster +pjc

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

ironclad \i"ronclad`\, a.
   1. having an outer covering of iron or steel; as, an ironclad
      war vessel.
      pjc

   2. so strong or secure as to be unbreakable; as, an ironclad
      contract.
      pjc irone

[4] : WordNet (r) 2.0

ironclad
     adj 1: inflexibly entrenched and unchangeable; "brassbound
            traditions"; "brassbound party loyalists"; "an
            ironclad rule" syn: brassbound
     2: without flaws or loopholes; "an ironclad contract"; "a
        watertight alibi"; "a bulletproof argument" syn: unassailable,
         unshakable, watertight, bulletproof
see also:
brassbound unassailable unshakable watertight bulletproof 

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

53 moby thesaurus words for "ironclad":
   armed cap-a-pie, armor-plated, armored, constant, dour, firm,
   fixed, fundamentalist, hard, hidebound, immovable, immutable,
   impliable, in armor, in complete steel, in harness, inalterable,
   inexorable, inflexible, invariable, iron, ironbound, ironhanded,
   loricate, loricated, mailclad, mailed, muscle-bound, obdurate,
   obstinate, orthodox, panoplied, procrustean, purist, puristic,
   puritan, puritanic, relentless, rigid, rigorist, rigoristic,
   rigorous, rockbound, stiff, straightlaced, straitlaced, stubborn,
   unalterable, unbending, uncompromising, unmodifiable, unrelenting,
   unyielding

Ironclad >> I Words
Ironclad, definition of term: Ironclad
ironclad_pag1.html