1. Without flaws or loopholes
   "an ironclad contract";
   - unassailable, unshakable, watertight, bulletproof, unshakeable
    
2. Inflexibly entrenched and unchangeable
   "an ironclad rule";
   - brassbound
    
3. Sheathed in iron plates for protection
   "The ironclad warship was considered invincible in its time"

1. A wooden warship of the 19th century that is plated with iron or steel armour
   "The ironclad changed naval warfare during the American Civil War"

Derived forms: ironclads

See also: incontestable, incontestible, inflexible, sheathed

Type of: combat ship, war vessel, warship

Encyclopedia: Ironclad