Clad means covered or dressed in something. When a knight is clad in armor, metal plates cover his body from head to toe. When a mountain is clad in snow, a white blanket covers its peaks and slopes.

The word has an old-fashioned, formal sound. You wouldn't say “I'm clad in jeans today,” but you might read in a story about a hero clad in a red cape or a castle clad in ivy. Writers use it to create a more dramatic or poetic feeling than simply saying “wearing” or “covered with.”

Clad also appears in compound words describing what something is covered with. A building might have copper-clad walls, meaning thin sheets of copper cover its exterior. Ships sometimes have steel-clad hulls to protect them. When ironclad warships appeared during the Civil War, they revolutionized naval warfare because their ironclad hulls could withstand cannonballs that would sink wooden ships.