Armor is protective covering worn to prevent injury in battle or other dangerous situations. Medieval knights wore metal armor made of interlocking plates or chain mail to shield themselves from swords, arrows, and lances. Roman soldiers wore armor made of bronze or leather. Japanese samurai developed their own distinctive armor with overlapping metal scales laced together with silk cords.

Modern soldiers still wear armor, though it looks quite different: bulletproof vests made of strong synthetic fibers like Kevlar protect against bullets and shrapnel. Police officers wear similar protective vests. Even athletes wear armor of a sort: catchers in baseball wear chest protectors and shin guards, while football players wear padded helmets and shoulder pads.

The word can also describe the tough protective covering of animals. An armadillo has bony plates forming natural armor across its back. Knights of old borrowed this idea from nature: they noticed how turtle shells and insect exoskeletons protected vulnerable creatures, then created human versions from metal and leather.

People sometimes use armor metaphorically to describe emotional protection. When someone puts up emotional armor, they're guarding their feelings to avoid getting hurt. While physical armor protects the body, this kind of armor shields the heart, though too much can prevent genuine connections with others.