Definition of ironclads:
(adj) :
(figuratively) Solid or certain; not able to be disputed or questioned; irrefutable.
(adj) :
Covered with iron, steel, or (loosely) any other tough metal; armor-plated.
(n) :
(military) An armor-plated warship, (especially) one preceding the invention of harveyized steel.
(n) :
A ship, vessel, or vehicle with a covering of iron, steel, or (loosely) any other tough metal.
(adj) :
(figuratively) Rigorous; severe; exacting.
(adj) :
(figuratively) Stubborn; inflexible.