ironclad

adj

1. Covered with iron, steel, or (loosely) any other tough metal; armor-plated.

   “Unlike the average vehicle, cash delivery vans are ironclad and almost unstoppable.”

   “In that flickering pallor it had the effect of a large and clumsy black insect, an insect the size of an ironclad cruiser, crawling obliquely to the first line of trenches and firing shots out of portholes in its side.”

2. (figuratively)Solid or certain; not able to be disputed or questioned; irrefutable.

   “The suspect had an ironclad alibi for his whereabouts on the night of the crime.”

3. (figuratively)Rigorous; severe; exacting.

   “an ironclad oath or pledge”

   “Observers of the day considered his rule more ironclad than that of the Prendergast machine in Kansas City, or even Tammany Hall in New York.”

4. (figuratively)Stubborn; inflexible.

   “He is in his seventieth year, and has done work enough in his life to try the most ironclad constitution.”

   “All the previous articles had only elicited a growl here or there from a hide-bound Catholic or from an iron-clad Evangelical, but now his post-bag was full.”

   “Even if you’ve run an ironclad household budget and managed your retirement accounts on your own, you’re about to be at a level of wealth in a different stratosphere. It’s time to hire professionals.”

noun

1. A ship, vessel, or vehicle with a covering of iron, steel, or (loosely) any other tough metal.

   “He turned again to the nearest land ironclad, advancing now obliquely to him and not three hundred yards away, and then scrambled the ground over which he must retreat if he was not to be captured.”

2. An armor-plated warship, (especially) one preceding the invention of harveyized steel.

   “About a couple of miles out lay an ironclad very low in the water, almost, to my brother's perception, like a water-logged ship. This was the ram Thunder Child.”

3. A wooden warehouse with an outer skin of corrugated metal.