Bald means having little or no hair on the head. Some people are born bald and grow hair as babies, while others lose their hair gradually as they grow older. By the time many men reach their fifties or sixties, they've gone completely bald or have only patches of hair remaining.

Baldness happens naturally because of genetics: if your father or grandfather is bald, you might become bald too. Some people lose their hair because of medical treatments or health conditions. Others shave their heads by choice, making themselves bald on purpose.

The word can describe anything smooth and bare where you'd normally expect covering. A bald tire has lost its tread and become dangerously smooth. A bald eagle isn't actually bald but has distinctive white feathers on its head that make it look bald from a distance, which is how it got its name.