- Covered in ferrous metal - Dressed in armour that is watertight? - Inflexible, rigid - Unbreakable (agreement) - Watertight - Clad in iron; protected or covered with iron, as a vessel
for naval warfare. - Rigorous; severe; exacting; as, an ironclad oath or
pledge.
- Watertight chamber - Watertight chambers - A chest to hold ammunition. - A four-wheeled carriage for conveying ammunition,
consisting of two parts, a body and a limber. In light field batteries
there is one caisson to each piece, having two ammunition boxes on the
body, and one on the limber. - A chest filled with explosive materials, to be laid in the
way of an enemy and exploded on his approach. - A water-tight box, of timber or iron within which work is
carried on in building foundations or structures below the water level. - A hollow floating box, usually of iron, which serves to
close the entrances of docks and basins.